Sen. Elizabeth Warren (D-Mass.) talks with President Obama in Washington on July 17, 2013. (Susan Walsh/AP)

Grass-roots liberal movements gave birth to two Democratic stars over the past decade: one who rode a wave of antiwar sentiment into the White House and the other who became the ideological standard-bearer in the party’s fight against big banks and corporate greed.

Now, in a battle few saw coming three years ago, President Obama and Sen. Elizabeth Warren (D-Mass.) are locked in an increasingly personal feud over a global trade deal that the president is trying to finalize in his last years in the White House. The clash has become a defining battle for Democrats, as Obama seeks — and Warren resists — “fast-track ­authority” from Congress that would give him a freer hand to cut trade deals.

The immediate goal for Obama is to make it easier to win approval of the Trans-Pacific Partnership (TPP), a trade deal with 11 other Pacific Rim nations that would affect roughly 40 percent of the global economy.

The Democratic infighting is beginning to shape the economic themes of the campaign to succeed Obama in the Oval Office. Warren has said repeatedly that she will not run but that she is focused on trying to force the likely Democratic nominee, Hillary Rodham Clinton, further to the left on economic issues.

Warren appears to have won the initial battles. Senate Democrats on Tuesday stalled an effort to move the Trade Promotion Authority measure as the overwhelming majority of them supported a friendly-fire filibuster.

Democratic infighting over a global trade deal is exposing both personal and policy issues between Sen. Elizabeth Warren (D-Mass.) and President Obama. The Post's Chris Cillizza explains the feud. (Tom LeGro/The Washington Post)

Clinton, meanwhile, has provided almost no cover for Obama on the trade issue even though she played a role in the early talks on the TPP and has long claimed the “pivot to Asia” as one of her most important accomplishments as Obama’s first secretary of state.

Against this backdrop, the bad blood between the White House and Warren has spilled into the open.

What began with a slight jab at Warren’s trade views — “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, on radio shows and from the official podium at the White House.

Over the weekend, Obama used a rather harsh turn of phrase — “a politician like everybody else” — against Warren, who has carefully constructed an image as a principled voice in the wilderness taking unpopular political stands to help the voiceless working class.

Warren returned fire in 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 on Tuesday morning.

Behind the scenes, according to Democratic aides and lobbyists, Warren is encouraging Democrats to oppose the TPA bill. She has paid particular attention to junior members of her state’s House delegation.

It is an unusual time in the Senate. Majority Leader Mitch McConnell (R-Ky.) — who once declared that his top goal was to make sure Obama was not reelected in 2012 — now boasts about a handwritten letter the president sent him after McConnell voted for Loretta E. Lynch’s appointment as attorney general.

And on trade they are open allies. Aides said McConnell and Obama talked strategy over the phone Monday. Republicans, in general, said they have never before worked this closely with the Obama White House on a domestic policy issue.

Allies of Warren were taken aback by the personal nature of the president’s remarks.

“I think the president was disrespectful to her, the way he did that. I think the president has made this more personal than he needed to,” Sen. Sherrod Brown (D-Ohio), who has led opposition to the trade legislation, told reporters after Tuesday’s vote.

Brown said that some of Obama’s comments were perceived as insults directed not only at Warren but also at other Democratic opponents of the trade deal.

But some pro-trade Democrats said they understood why the president feels so strongly that Warren was overreaching in her criticisms. “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.) said Tuesday.

The Obama-Warren relationship has never been particularly close, but it wasn’t openly hostile until recent weeks.

Since the late 1990s, as a Harvard law professor and expert on bankruptcy law, Warren has been an influential voice on long-term wage trends affecting the middle and working classes. At the time, she had few allies in Washington beyond then-Sen. Paul D. Wellstone (D-Minn.), whose late-night calls to her Cambridge, Mass., office she likes to recall in her speeches.

After the Wall Street crash of 2008, she served as the head of a congressionally appointed panel overseeing the implementation of a $700 billion bank bailout. She became a special adviser to Obama and had an important role in one of the key pieces of the 2010 Dodd-Frank law that rewrote regulations for financial institutions: the establishment of the Consumer Financial Protection Bureau.

Republicans made clear that they would filibuster any nominee to head the CFPB, and eventually Obama gave up on appointing Warren — to the dismay of many liberal activists, who by then had begun to view her as the more pure liberal fighter.

But the appointment to the relatively obscure CFPB turned out to be the best thing to never happen to Warren. Instead, Senate Democrats recruited her to return to Massachusetts to run against Sen. Scott Brown (R) in 2012.

With her future somewhat intertwined with the president’s, Warren used a high-profile speech at Obama’s nominating convention to break away from Brown in what looked like 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 — fueled by millions of small-dollar donors drawn to her message.

Warren’s tenure in the Senate has been focused on banking and Wall Street, and she has made countless appearances in liberal settings or with liberal media outlets to argue that wage stagnation is causing the middle class to fall behind.

Democrats largely latched onto this message for the 2014 midterm elections, and Warren became a star on the campaign trail, working for other candidates. But the effort paid little dividend to anyone but Warren. 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 prod fellow Democrats, including Obama and Clinton.

Clinton has responded by signaling that her 2016 campaign will embrace many Warren-
advocated ideas, seeking out the senator’s views in private meetings and writing a piece for Time magazine that praised Warren for holding “powerful people’s feet to the fire.”

Recently, Obama grew tired of Warren’s tactics on the trade bill — some of which resemble what Republicans used against the 2010 health-care law. The president is particularly irked by Warren’s representations that the ­Pacific trade deal is being kept secret. The White House points out that members of Congress are allowed to review its current stages in a classified room in the Capitol basement.

Obama also resents her assertion that future trade deals would roll back portions of the Dodd-Frank law.

“On most issues, she and I deeply agree,” Obama told Yahoo News on a visit to Nike’s headquarters in Oregon, where he trumpeted the trade deal. “On this one, though, her arguments don’t stand the test of fact and scrutiny.”