South Bend, Indiana, Mayor Pete Buttigieg and Sen. Elizabeth Warren, D-Mass., have ramped up their public feud in recent days, a conflict that highlights an increasingly evident dynamic in the Democratic presidential race: The party's class divides are as potent as its philosophical ones.
Buttigieg and Warren are both competing fiercely for white, college-educated voters, who polls suggest will play a big role in Iowa and New Hampshire - even as Warren promises far-reaching change that resonates with liberals and Buttigieg sells a more unifying message designed for moderates.
"If you just look at what their bases of support are, it would make sense for them to butt up against each other in a more definitive way," said Kenneth Baer, a Democratic strategist and former Obama administration official. "I'm sure they're seeing polls where they're going after the same people."
This represents a shift in how analysts, and the campaigns themselves, see the Democratic race. Many have spent months describing a leftist "lane" and a centrist one, but the competition between Warren and Buttigieg suggests it's more complicated.
While Sen. Bernie Sanders, I-Vt., and former vice president Joe Biden both have a certain appeal for working-class Democrats, despite their different platforms, Warren and Buttigieg both appeal to more educated voters.
Strategists and allies for both campaigns agree that the two candidates have taken note of that overlapping base.
For much of the campaign, their attacks have been asymmetrical, as Buttigieg has aimed an occasional snipe at Warren while she has largely tried to stay above the fray, never attacking the mayor by name.
That changed Thursday in Boston, when Warren unloaded on Buttigieg's practice of holding closed-door fundraisers.
"I think that Mayor Pete should open up the doors so that anyone can come in and report on what's being said," Warren told reporters. "Those doors shouldn't be closed, and no one should be left to wonder what kind of promises are being made to the people that then pony up big bucks to be in the room."
Warren's attack was designed to contrast with her approach of avoiding events with big donors.
In the first fundraising quarter, Buttigieg released the names of his bundlers, the people who collect large checks on his behalf, though has stopped the practice.
Buttigieg shot back Friday. "The odd thing about that fundraising is, she was for it before she was against it," he said.
That was a reference to Warren's decision to transfer more than $10 million to her presidential campaign from her Senate coffers, where she ran the kind of high-dollar fundraising program she disparages today.
Matt Paul, an Iowa-based Democratic strategist, said the growing combativeness reflects the approach of the Iowa caucuses on Feb. 3. "We're 60 days from the Iowa caucuses. Welcome to the majors. It's prime time," he said. "They're both doing well. The stakes are high; early-state voters are watching this."
Still, the Warren-Buttigieg fight has multiple fronts and has been simmering for months. Buttigieg leveled a sharp attack on Warren over health care in October, demanding to know in a Democratic debate why Warren could not explain how she would pay for her Medicare-for-all health plan.
"Your signature, senator, is to have a plan for everything - except for this," Buttigieg said. Warren released a $20 trillion financing plan two weeks later.
Buttigieg has also attacked Warren's education policy. A fight has even broken out over their fighting, with Buttigieg saying Warren is "so absorbed in the fighting that it is as though fighting were the purpose."
Warren began singling out Buttigieg several weeks ago in Iowa, when she was asked by reporters about his push to get her to release more of her tax returns.
"I understand that there are some candidates who want to distract from the fact that they have not released the names of their clients," Warren said.
She did not mention Buttigieg's name, but it was a clear reference to his work for the consulting firm McKinsey & Co. Buttigieg has said little about that work, citing a nondisclosure agreement; meanwhile, McKinsey has suffered a spate of bad headlines, including for its work advising drugmaker Johnson & Johnson on increasing opioid sales.
Lis Smith, a spokeswoman for Buttigieg, has said he is trying to free himself from a nondisclosure agreement he signed with McKinsey. "We are working on this- stay tuned," she said.
McKinsey's media team did not reply to an email seeking information about the agreement or the status of any talks about it. But Buttigieg has begun criticizing his former employer as representing an unappealing aspect of corporate culture.
On Friday, a voter in New Hampshire asked him why he was not being more open about his time at the firm.
"The bind I'm in right now is I believe in keeping your word, and I signed a legal document about client names," Buttigieg said. "And I am calling on McKinsey to release me from that so that client list can go out."
He added: "It's not like I was running the place. It was my first job out of school. But I think the American people deserve to know."
Buttigieg's team is trying to highlight Warren's own years of work advising clients such as Dow Chemical when she was a prominent legal expert, hoping to pierce her image as an anti-corporate crusader.
"If @ewarren wants to have a debate about transparency, she can start by opening up the doors to the decades of tax returns she's hiding from her work as a corporate lawyer- often defending the types of corporate bad actors she now denounces," Smith tweeted.
Warren's team has said she has no plans to release additional tax records, noting that she has already released 11 years' worth. Buttigieg has released 12 years of tax records, which include the time he worked for McKinsey but do not provide extensive detail.
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