When Hillary Clinton bagged an endorsement from the Service Employees International Union on Nov. 17, she secured more than just the symbolic support of one of the nation's most influential labor organizations.

SEIU's decision to back her over Vermont Sen. Bernie Sanders means she will get millions of dollars, thousands of volunteers and hundreds of targeted ads for her presidential campaign, courtesy of Big Labor.

SEIU's revenue last year topped $321 million, and it's ready to spend a big chunk of that to get Clinton into the White House.

Beyond money and donations, the union controls another key weapon in Clinton's arsenal: Amalgamated Bank, an institution rapidly becoming the Left's financier of choice.

Amalgamated Bank was founded in 1923 by the New York City garment workers union, the Amalgamated Clothing Workers of America. It's where many working families deposted their earnings. In recent years, however, the bank has morphed into an ally of the Democratic Party, bankrolling a growing number of political campaigns and organizations.

As the practical influence of unions has waned, the labor movement has worked to grow its influence within the Democratic Party. (Bloomberg photo)

SEIU controls Amalgamated Bank, which it took over in 2009 when it intervened in a bitter legal battle between warring factions of the same union. He who pays the piper calls the tune, and so SEIU, with Amalgamated in its grasp, holds considerable sway on the Left. Union dues and Democratic Party assets flow into the bank, while campaign loans and corporate activism flow out of it.

Amalgamated's partisanship is neither illegal nor unethical according to Federal Election Commission guidelines. But critics say the bank's unique blend of politics and investment gives Big Labor yet another avenue of influence in electoral politics.

Tangled 2016 finances

Clinton deposited her massive campaign war chest at Amalgamated this year. In September 2014, Ready for Hillary, a political action committee that backed her before she officially launched her campaign, moved its money from Bank of America to Amalgamated. Its executive director, Adam Parkhomenko, said the shift was about "putting our money where our values are."

Less than a month later, Amalgamated gave $1 million to Ready for Hillary, according to the Center for Responsive Politics.

Bank of America has not forsaken the Clinton cause. Executives from the Wall Street giant have poured nearly $90,000 directly into her presidential campaign, which places them among her top donors.

SEIU also has a history with Bank of America. In 2010, union members petitioned to oust the chief executive, Ken Lewis. The union owed $68.7 million to Bank of America at the end of last year, according to its financial forms, making the Wall Street titan its biggest creditor.

SEIU announced its endorsement of Democratic nominee Hillary Clinton in November despite the fact that Clinton doesn't support a $15 minimum wage.

In a high-profile shift, the Democratic National Committee moved its finances out of Bank of America and into Amalgamated in August 2012, signaling the party's deepening ties to Big Labor on the eve of President Obama's reelection. The DNC owed $15 million to the SEIU's bank at that time, FEC records show, and it still owes $10 million, a sum it will have to repay or refinance by June of next year.

The Clinton campaign, routing its political finances through Amalgamated, paid the union bank $15,097 in fees between April and September, FEC records show.

Because SEIU's endorsement came after the most recent financial disclosure deadline, its contributions directly to the Clinton campaign since that time are not yet public.

But the union had already spent heavily against Republican presidential candidates in coordinated attack campaigns that included Facebook, Twitter and Google ad buys. Some of the $342,000-plus it has spent on anti-GOP messaging in the presidential primary predated its decision to back Clinton.

SEIU has spent roughly $85,000 each on campaigns against Jeb Bush, Ted Cruz, Marco Rubio and Donald Trump.

Through its political action committee, SEIU has already poured more than $15 million into the race despite only recently settling on Clinton as its top candidate.

Matt Patterson, executive director of Center for Worker Freedom, an arm of the conservative Americans for Tax Reform, said SEIU's decision to back Clinton ruffled feathers within the union's lower ranks.

"What strikes me about the SEIU endorsement is that there's a lot of the local chapter leadership that was very upset by this, because they want to support Bernie Sanders," who is more identified with ordinary workers, Patterson said.

Although Clinton does not support a $15 minimum wage and opposes the Keystone Pipeline, two positions that put her at odds with SEIU's stated goals, Patterson said Clinton is still a natural ally for the union.

"In reality, there's very little daylight between Hillary and any labor leadership," he noted.

Sanders supporters point to Clinton's long list of corporate donors and lukewarm support for a minimum wage hike as evidence that the Vermont senator is a better fit for the labor movement.

However, Clinton is quickly consolidating support among the country's largest labor players, racking up endorsements from more than a dozen major unions.

SEIU's well-placed bet

SEIU gained control of Amalgamated by inserting itself into a rival union's feud, swallowing up the side that won the fight over the bank and, later, dumping that organization's existing leader in a move that sealed SEIU's ownership of Amalgamated in 2011.

Ivan Osorio, editorial director at the Competitive Enterprise Institute, said the bank was a significant prize for SEIU regardless of whether it drove the union's decision to get involved in the 2009 split of Unite Here.

"Clearly, Amalgamated is a major asset. So for SEIU, it's clearly a big get," Osorio said. "Whether that was the main motive, of course, only those who were directly involved could say for sure. It is clear that acquiring Amalgamated really was a boost to SEIU. That's undeniable."

Neither Amalgamated Bank nor SEIU responded to requests for comments.

SEIU's push to acquire Amalgamated came just months after it took out a $15 million loan from the bank, according to the California Professional Public Employees Association. Amalgamated was then owned by Unite Here, a hybrid union formed by the 2004 fusion of textile and hotel service unions.

"What does seem clear is, as soon as the fight within Unite Here at the time appeared poised to lead to a potential split, SEIU was pretty quick to step in," Osorio noted.

Before 2004, Amalgamated was owned solely by the Union of Needletrades, Industrial and Textile Employees, which grew out of the garment workers' union that founded the bank.

Unite brought Amalgamated to a high-profile merger with the Hotel Employees and Restaurant Employees union. This union had better membership prospects as the textile industry continued its shift overseas, but Unite's control of the bank made it an attractive partner, according to the Capital Research Center.

The merged Unite Here union began to crumble in 2009 as its leaders sparred over resources and strategy.

Bruce Raynor, president of Unite Here, called the merger an "abject failure" in February 2009 amid tensions with John Wilhelm, president of the Hotel Employees & Restaurant Employees union. Wilhelm later became president of Unite Here.

Bruce Raynor, president of Unite Here, called the merger an "abject failure" in February 2009. (AP File Photo)

Wilhelm also sat on the board of Amalgamated, a hotly contested asset in the break-up of Unite Here. Raynor, who struggled to divert funds to local affiliates loyal to him as relations between Unite and the hotel union soured, was determined to keep control of Amalgamated while peeling supporters from Unite Here.

"Once it became clear that Wilhelm had leadership support in that dispute," Juan Gonzalez of the New York Daily News wrote in April 2009, "Raynor rushed to rewrite the bank's bylaws in December [2008] to assure himself control of Amalgamated's board of directors. He then ousted Wilhelm as a bank director."

With two different visions for their fused union, which they had attempted to lead in tandem, Wilhelm and Raynor fought bitterly over who would get what as a break-up of the organization became increasingly probable.

Wilhelm allegedly hired security guards to break into Raynor's office out of concern that the Unite leader was preparing to leave with sensitive documents, while Raynor reportedly siphoned $12 million from Unite Here to finance an eventual secession.

In March 2009, Raynor led a group of loyal affiliates out of Unite Here and formed Workers United, which consisted of many of the same members as the former Unite.

Within days, Workers United had affiliated with SEIU, which spent millions subsidizing its new arm. In fact, SEIU was forced by budget constraints to lay off 75 workers the same month it started pumping funds into Workers United, according to the pro-union outlet Labor Notes.

Andy Stern, then the head of SEIU, later compared his decision to fund one side of the court battle over Unite Here's assets to the decision to invade Iraq.

"It's like saying, 'We're going into Iraq and we'll be out in a month,' and after six years you say, 'If I knew it would have been six years, is this what I would have done?' I made a decision based on what I thought was going to happen," Stern said in a 2010 interview of the pitched legal battle between factions controlled by Wilhelm and Raynor.

Workers United and what was left of Unite Here ultimately reached an agreement in July 2010, with Wilhelm's Unite Here maintaining control of the former garment union's New York headquarters, which was valued at roughly $70 million, as well as most of the members Workers United had attempted to pry from the merger and an additional $75 million in financial assets. Raynor's Workers United, now owned and backed by SEIU, won Amalgamated.

Less than a year later, Raynor was forced out of his position as chairman of Amalgamated's board over accusations that he "fibb[ed] about $2,300 in meals with a female union executive," according to Crain's New York Business.

Amalgamated Bank was founded in 1923 by the New York City garment workers union, the Amalgamated Clothing Workers of America. It's where many working families deposited their earnings. (Graeme Jennings/Examiner)

After Raynor was removed over expense account discrepancies, a move he characterized as retaliation for backing the losing candidate in the race to replace a retiring Stern as president of the union, SEIU named one of its own to the chairmanship of Amalgamated. Noel Beasley, a vice president at SEIU, took the helm of the bank's board in August 2011.

Keith Mestrich, another SEIU alumnus, became president of Amalgamated last year, further cementing SEIU's control of the bank.

Unions and Democrats cozy up

As the practical influence of unions has waned with time, the labor movement has worked to grow its influence within the Democratic Party. The push to consolidate its political power reflects Big Labor's overall shift from affiliated local chapters to centralized union conglomerates.

Daniel Schlozman, political science professor at Johns Hopkins University and author of When Movements Anchor Parties: Electoral Alignments in American History, said the labor movement's focus on the Left is a reaction to its dwindling numbers.

"Unions, although their membership is way down, especially in the private sector in the last three-plus decades, have chosen to concentrate their resources and punch above their weight by focusing on the Democratic Party," Schlozman said.

Union membership rates fell to a 100-year low of 11.1 percent last year, according to the Bureau of Labor Statistics.

At the same time, unions' political spending is reaching new heights. Between 2002-14, SEIU poured more money into politics than any other organization, union or otherwise, the Center for Responsive Politics found. Ninety-nine percent of the $224 million it spent on political campaigns and causes went to Democrats.

Schlozman said the labor movement has sought new ways of remaining relevant in an ever-shifting political landscape.

"Unions have to ask: What are the different sort of strategies they can use? So one strategy is to find allies among both Republicans and Democrats," he said.

Another, Schlozman noted, is to "try to be a social movement and go on the streets."

But Schlozman said the most successful strategy by far has involved a close relationship between unions and Democratic politicians.

"All the other strategies that aren't party politics ... have got real perils," he said.

"As labor retreats from having real influence in determining the political agenda in the polity as a whole, it's retrenching into alliance with the Democrats, because that's what they do," he added. "That's its core."

Schlozman said the ties between unions and Democrats have become "deeper and narrower," but not broader.

Patterson noted Democrats benefit from more than just unions' political spending.

"Political campaigns depend on a lot of grassroots volunteer action. Labor can turn that out," he said. "They can get people to go door-knocking. They can get people to send out mailers. Having that manpower and that pretty secure source of funds is really key to the Democratic Party."

In announcing SEIU's endorsement of Clinton in November, Mary Kay Henry, the union's president, vowed to deliver just such support from the ranks of its 2 million members.

"Labor has always been a source of funding and support for the Democratic Party, but as labor shrinks as far as a percentage of the working population, I find that they're getting more and more radicalized," Patterson added. "As their numbers decrease, they've become more shrill and vocal and outright left-wing."