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What if Elizabeth Warren runs for president in 2016?

Senator Elizabeth Warren, a Democrat from Massachusetts. (Andrew Harrer/Bloomberg)

What if Hillary isn’t the one?

Eight years ago, the idea seemed as preposterous as it does now. But, at a recent event in Boston organized by the super PAC Ready For Hillary, a group building a nationwide network of Hillary Clinton supporters in the likelihood she runs for president in 2016, Clinton wasn't the only talked-about prospective Democratic candidate.

Another, much more daring name was floating in the ether, that of someone renowned for taking on big, moneyed institutions: Massachusetts Sen. Elizabeth Warren.

Former Rep. Barney Frank, D-Mass., who worked closely with Warren before she entered the Senate on the Dodd-Frank reform of Wall Street, was there to boost Clinton -- but, at the same time, he candidly predicted Warren would run.

"Oh, I think yes," Frank told the State House News Service. "In the first place, why would you want to get into a profession and have no interest in rising to the top of it? I don't know anybody who has that."

Frank also knows Clinton, who, as she has traveled the country during the past few months, mostly for paid speaking engagements, has taken measured, incremental steps back into the political arena, fostering an air of inevitability. And, should she run, the barrier to entry would be high for any other Democrats: In public surveys, Clinton has polled at least 50 points, and sometimes much more, ahead of anyone else in her party.

But there is a potent and growing curiosity about whether a different type of Democrat could pose a viable challenge to Clinton, or lead the field in the event Clinton decides not to run — and whether Warren is the woman for the task.

Progressives have clamored for a candidate from the “Elizabeth Warren wing” of the party, who would run to the left of Clinton. Were Warren to run, she would almost certainly embrace that niche, with good reason: She has been a longtime advocate for government oversight of and intervention in the banking industry.

The liberal appeal is obvious, but there is less clarity about what shape her campaign would take.

Warren, who rose to prominence as a vocal foe of the banking industry after the financial meltdown, boasts a lengthy roster of powerful Democratic allies who could help her put together a credible campaign for president. But, as of now, Warren has only a bare-bones political infrastructure outside of Massachusetts.

Her political action committee, the PAC For A Level Playing Field, has pledged to support Democratic Senate candidates during the 2014 midterm election cycle, but it doesn't nearly match the heft of a presidential-level super PAC. The organization ended March with a little more than $300,000 in the bank, whereas Republican candidates weighing presidential bids have raised millions of dollars.

The Clinton money machine, meanwhile, would be powered by the heavyweight super PAC Priorities USA Action, which backed Barack Obama in his successful runs. Ready for Hillary would lead grassroots organizing.

Seth Bringman, a spokesman for Ready For Hillary, would not speculate how its tack would change were Warren to enter the race. “Our focus is simply to build a list of enthusiastic Hillary supporters who can be activated the moment she makes a decision,” Bringman said.

In face of such significant and well-organized establishment support for Clinton, Warren would almost certainly have to rely on a campaign of grassroots activism to compete. Just as Obama was able to wrestle the Democratic nomination away from Clinton in 2008 by capturing the imagination of the party base, Warren’s threat to Clinton would be her appeal to those yearning for a bolder progressive agenda.

Indeed, Warren will be the keynote speaker this summer at Netroots Nation in Detroit, a progressive confab that will draw some of her ardent -- and some of the party's most passionately liberal -- supporters.

Still, there is ample reason to conclude Warren would not run for president if Clinton chooses to do so. Although there are numerous precedents for one-issue candidates running to bring attention to their pet policies, Warren isn’t one to run without a path to victory.

“Run and lose. Gee, that sounded like fun,” Warren wrote in her newly released memoir, A Fighting Chance. "Maybe I'd do that right after I deliberately slammed my fingers in a car door."

“Once I was in,” she wrote later of her Senate bid, “I knew that the only way I could do anyone any good was to win — so I intended to win.”

Warren was a first-time candidate when she challenged Republican Sen. Scott Brown in one of the most closely watched Senate races in 2012, and she faced many of the obstacles she would need to surmount should she run for president.

Warren, who turns 65 in June, was 62 at the time she considered running for Senate. “Wasn’t I supposed to be thinking about rocking chairs and retirement plans, not crazy new ventures that require eighteen-hour days and months of grueling work?”

And Warren worried she could not compete with the fundraising prowess of Brown, who had already begun to amass an intimidating campaign war chest.

“Okay, so the liability stack was high, and right at the top was something buried in my heart of hearts — I really didn’t want to run,” Warren wrote. “I’d had enough of Washington. I’d never yearned for a life in politics.”

Her family members counseled her against running. But, ultimately, she shrugged off their warnings and her doubts.

“Could I really stand on the sidelines and stay out of this fight?” she wrote.

Warren's age may ultimately be a factor in deciding whether to run. Because she looks younger, many voters and even journalists assume she's in her early 60s. But she's Clinton junior by only 16 months, and both women doubtless understand that 2016 is probably their last, best chance to make it to Pennsylvania Avenue.

Some members of Warren's Senate campaign team are still in her inner political circle, and would likely be intimately involved in her decision to run for president and in planning her campaign.

There’s Dan Geldon, a former campaign adviser to Warren and her current deputy chief of staff, who one Democrat described as Warrenland’s “quiet warrior.” Doug Rubin, who former Obama adviser David Axelrod recommended to run Warren’s Senate campaign. Mandy Grunwald, a longtime ally of Clinton, who counseled Warren early on whether to run and later advised her campaign. And Mindy Myers, a key figure in Warren’s fold and her chief of staff, who ran Obama’s New Hampshire campaign in 2008 before leading Warren to victory in 2012.

“She was calm and steady and had great judgment, a perfect counterbalance to my damn-the-torpedoes-full-steam-ahead tendencies,” Warren wrote of Myers.

If Warren is susceptible to spontaneity, however, her book tour has been a lesson in restraint — and in making clear to supporters that the 11-city jaunt, easily confused for a presidential-campaign trial-run, is not that. The book tour did not take Warren to any key early-primary states, such as Iowa or New Hampshire, which would have indicated serious interest in a presidential bid.

“Run, Liz, run!” one woman shouted at Warren’s stop in Union Square in Manhattan. But, Warren assured the crowd, “I’m not running for president.”

She said the same thing in an interview with ABC's David Muir April 21, who then pressed her for a Shermanesque answer: "There's nothing that could change your mind?"

"David, like I said, I'm not running for president," Warren said, avoiding a more definitive response. She went on to say that she thought Clinton was "terrific," adding, "We gotta stay focused on these issues right now."

For their part, Republicans consider her a possible opponent and are following Warren on her tour.

“We're monitoring Warren, including having trackers at her book tour events,” said Tim Miller, who directs America Rising PAC, one of the prominent Republican opposition-research outfits. “We're also particularly focused on research that wedges her against Hillary with progressives.”

That conflict between the progressive and moderate wings of the Democratic Party, neatly embodied by a hypothetical face-off between Warren and Clinton, is what makes many in the party uneasy -- and what might have caused a range of Democrats with ties to either potential candidate to decline to comment for this story.

But the motif isn’t going away. And the echoes of 2008 — the seemingly inevitable candidate versus the activist — might be too familiar for the comfort of Hillary backers.

As for Warren's disavowals of interest in running, the same progressive Democrats likely to support her recall that then-Sen. Barack Obama said the same for much of 2006 — until he didn’t.

"I would say I am still at the point where I have not made a decision to pursue higher office, but it is true that I have thought about it over the last several months," Obama finally said on NBC’s “Meet The Press” in October 2006.

Why had he said he wouldn’t run? He responded, "That was how I was thinking at that time.”