The liberal grass-roots movement gave birth to two huge stars over the last decade, one who rode a wave of anti-war support into the White House and the other who became the ideological standard-bearer in the fight against big banks and corporate greed.
Now, in a battle few saw coming three years ago, President Barack Obama and Sen. Elizabeth Warren, D-Mass., are locked in an increasingly personal dispute over a mammoth global trade deal that the president is trying to finalize in his last years in the White House. The faceoff has become the defining battle in the Democratic Party, as Obama seeks "fast-track" trade authority from Congress, which would allow him a freer hand to cut trade deals.
The ultimate goal is approval of a deal with 12 Pacific-rim nations representing roughly 40 percent of the global economy.
Moreover, this dispute sets the stage for the campaign to succeed Obama in office, as the firebrand senator has opted not to run but instead is focusing her effort on moving the likely Democratic nominee, Hillary Rodham Clinton, farther to the left.
On two fronts Warren appears to have won initial battles. The Senate on Tuesday ran into a filibuster of the Trade Promotion Authority measure that would grant Obama fast-track powers to pass global deals, as the overwhelming majority of Democrats blocked consideration of the legislation.
Also, Clinton has provided almost no cover for Obama on the trade issue even though she played a role in shaping the early stages of talks on the Trans-Pacific Partnership and has long claimed the "pivot to Asia" as one of her most prominent accomplishments as Obama's first secretary of state.
Against this backdrop, the bad blood between the White House and Warren has spilled out into the open.
What began with a slight jab at Warren's opposition to trade legislation — "she's wrong on this," Obama told MSNBC three weeks ago — has escalated into a series of daily barbs and retorts carried out on cable TV and Internet interviews, radio shows and from the official podium at the White House.
Over the weekend Obama used a turn of phrase — "a politician like everybody else" — that was a deep cut against Warren, who constructed the image of being the principled voice in the wilderness taking unpopular political stands to try to help the voiceless working class.
Warren returned fire in a series of interviews and appearances Monday and Tuesday, accusing the president of duplicity because he "won't actually let people read the agreement" before Tuesday's procedural vote in the Senate.
"The president is asking us to vote to grease the skids on a trade deal that has largely been negotiated but that is still held in secret," she told NPR Tuesday morning.
Behind the scenes, according to Democratic aides and lobbyists, Warren is helping encourage Democrats to oppose the TPA bill. She has had a particular focus on junior members of her state's House delegation.
It is an unusual time in a Senate where the majority leader, Mitch McConnell, R-Ky., once proudly boasted that his top 2012 goal was see Obama defeated but now boasts about the handwritten letter the president sent him after McConnell voted for Attorney General Loretta Lynch.
Aides said McConnell and Obama spoke again by phone Monday to talk strategy on approving the trade deals, and Republicans say they have never worked this closely with White House officials on any domestic policy issue during this presidency.
Allies of Warren and Obama seem taken aback by the events. "President Obama has never attacked Republican Leader Mitch McConnell the way he's attacking Elizabeth Warren," the Progressive Change Campaign Community, a liberal group that wants Warren to run for president, wrote to its supporters Tuesday.
"I mean, I think it's a president that wants a trade agreement, and I think a member of his party is going out of her way, and that bothers him, so that's all I can say," Sen. Dianne Feinstein, D-Calif., who is tentatively supporting the trade deals, said Tuesday.
The Obama-Warren relationship has never been particularly close, but it also hasn't ever been openly hostile until recent weeks.
Since the late 1990s, as a Harvard law professor with an expertise in bankruptcy, Warren has been an influential voice among liberals who have studied long-term wage earnings by the middle and lower class. Those days found her few allies in Washington, other than the late Sen. Paul Wellstone, D-Minn., whose late-night calls to her Cambridge office she likes to recall in her speeches.
Following the Wall Street crash of 2008, she served as the head of a congressional oversight panel on how the $700 billion bank program was implemented and then became a special adviser to Obama to help create one of the key pieces of the 2010 Dodd-Frank law that rewrote regulations for financial institutions, the Consumer Financial Protection Bureau.
The initial indications were that Warren would get the formal nomination to run the CFPB, but that required Senate confirmation and Republicans made clear they would filibuster any nominee to run an agency that they did not support.
Eventually Obama gave up on Warren's nomination, to the dismay of liberal activists who by then had begun to view her as a more pure liberal fighter. But losing out on running the relatively obscure agency turned out to be the greatest political event to never happen to Warren, as instead Senate Democrats recruited her to return to Massachusetts to run against Sen. Scott Brown, R, in 2012.
Their political futures somewhat intertwined when Warren used a high-profile speech at Obama's nominating convention to break away from Brown in what had been a neck-and-neck race until the early fall.
She raised more than $42 million for her Senate race, a staggering sum for a first-time candidate for office. She used the energy of small-dollar donors drawn to her message in a manner that Obama first used in his 2008 campaign to defeat Clinton in the primary and then win the general election.
Warren's tenure in the Senate has been keenly focused on banking and Wall Street causes, making countless appearances in liberal settings or interviews with liberal media outlets to argue that wage stagnation has left the middle class falling behind.
Democrats largely latched onto this message for the 2014 midterm elections, and Warren became a star on the campaign trail for candidates, but it showed little dividend to anyone but the senator. Democrats lost nine Senate seats and were relegated to their smallest number of House seats since before the Great Depression.
This year Warren has been more willing to poke at her fellow Democrats, including Obama and Clinton.
Clinton has responded by signaling that her 2016 campaign will embrace many of the Warren-advocated ideas, seeking out the senator's views in private meetings and even penning a piece for Time Magazine's "100 Most Influential People" list that praised Warren for holding "powerful people's feet to the fire."
Recently, Obama grew tired of Warren's tactics on the trade bill. The president is particularly irked by Warren's representations that the Pacific trade deal is being held in secret, when members of Congress are allowed to review its current stages in a classified room in the Capitol basement.
Also, he resents her assertion that future trade deals would roll back portions of Dodd-Frank.
"On most issues, she and I deeply agree," Obama told Yahoo News while at Nike's headquarters in Oregon trumpeting the trade deals. "On this one, though, her arguments don't stand the test of fact and scrutiny."