Hillary Clinton finds herself embroiled in a campaign-threatening scandal that almost didn't happen.

The Democratic presidential front-runner is under siege, fending off questions almost daily about her home-brew server and whether she trafficked in classified, sensitive government information on the private email account she used during her tenure as secretary of state. But for a congressional investigation into the tragic Sept. 11, 2012, terrorist attacks on the U.S. consulate in Benghazi, Libya — an inquiry that didn't begin until nearly two years later — Clinton's secret server might still be a secret.

It wasn't until the House Select Committee on Benghazi, established by a determined Speaker John Boehner, R-Ohio, in May of last year, started digging by hand through 15,000 pages of emails turned over by the State Department that Clinton's use of private email was uncovered. Experienced committee investigators, looking for information about Benghazi, stumbled onto eight email messages that contained what turned out to be Clinton's private email address. That accidental discovery led others to the home-brew server.

"This is team of professional investigators — lawyers, military, congressional staff, former executive branch — that really dug into this line by line to make sure they weren't missing anything," select committee spokesman Jamal Ware told the Washington Examiner. "Eight emails in 15,000 pages — you have to be paying attention."

Clinton, her campaign and outside supporters insist that she did nothing wrong or illegal in using private email and a private, non-government server while serving as President Obama's first secretary of state. They continue to push back on the suggestions of improper and possible illegal handling of classified information as a partisan witch hunt, with the House Select Committee on Benghazi, and its former prosecutor chairman, Rep. Trey Gowdy, R-S.C., as the chief culprits.

That defense has been harder for Clinton to make since the Justice Department and the FBI began examining whether Clinton and some top aides mishandled classified information through the private email server that she kept at her private residence in Chappaqua, N.Y. "She didn't really think it through. And, she has said, had she, she would have done it differently," Clinton campaign communications director Jennifer Palmieri conceded Wednesday, during an interview with Bloomberg Politics.

Even as the Republican machine attacks Clinton relentlessly over the email scandal, the party is exceedingly careful about how it discusses the select committee.

The panel is investigating a terrorist attack that occurred less than eight weeks before the 2012 elections and left four Americans dead, including Ambassador Christopher Stevens. GOP officials and senior party strategists don't want to appear as though they are profiting politically from a major national tragedy. Privately, however, Republican insiders acknowledge the crucial role the select committee played in jumpstarting an investigation that has put Clinton in a bind.

"Incredibly, she has done something no one else could do: knock Donald Trump out of the headlines," said a senior Republican strategist, who requested anonymity in order to speak candidly. "It has changed the course of the election."

Boehner this year has been somewhat of a punching bag for conservatives disgruntled with Washington — and that includes some of the members inside his own conference. But the select committee, and the problems it eventually created for Clinton that have so delighted grassroots Republicans, might not have been given a green light if not for the speaker's persistence to get to the bottom of what happened in Benghazi.

Throughout the initial investigation into the attacks, managed by the five House committees of jurisdiction, Boehner had to prod some of the chairmen, who proved resistant, to keep up the pursuit, particularly then-Intelligence Chairman Mike Rogers of Michigan. He kept in regular touch with Reps. Jason Chaffetz of Utah and Devin Nunes of California, now the chairmen of Oversight and Government Reform and Intelligence, respectively, to keep tabs on the pace and progress of the investigation in their committees.

Behind the scenes, Boehner did a little investigating of his own, as Stephen F. Hayes and Thomas Joscelyn laid out in a December article in the Weekly Standard.

Boehner initially resisted calls from conservatives off of Capitol Hill to form a select committee to investigate Benghazi. He believed the committees of jurisdiction over the matter should have first crack at fulfilling their oversight responsibilities. They had expertise and subpoena power, and Boehner worried that jumping the gun on a special panel might invite charges that he was politicizing the issue. Democrats maintain that the GOP investigation into Benghazi has been political from the start.

But when Judicial Watch, a conservative third party group, obtained through a Freedom of Information Act lawsuit documents from the Obama administration related to the Benghazi investigation that the congressional committees had been unable to secure, Boehner decided that a select committee was necessary. Gowdy was Boehner's first and immediate choice for chairman, a pick also pushed by then-House Majority Leader Eric Cantor, R-Va. The GOP panel members were picked from the committees of jurisdiction.

Since then, Boehner has taken on the role of protector of the select committee.

Gowdy's crew doesn't have the manpower or the resources to push back against Democratic attacks on its intentions and work product, so the speaker's leadership office has been handling it. On Wednesday, the speaker's office issued a press release titled "No joke, 5 whoppers from Hillary Clinton's press conference," related to a news conference with reporters she held on Tuesday in which she was pressed on the email scandal.

"The stonewalling and obstruction from this administration has been, in the speaker's view, absolutely disgraceful," Boehner spokesman Kevin Smith said.

Disclosure: The author's wife works as an adviser to Scott Walker.