The former South Bend mayor and the senator from Minnesota are competing for the same voters, and the fight is getting nasty.
In one corner, we have a mild-mannered Midwestern moderate, looking to appeal to centrist Democrats and disillusioned Republicans.
And in the other corner ... we have a mild-mannered Midwestern moderate, looking to appeal to centrist Democrats and disillusioned Republicans.
Pete Buttigieg and Amy Klobuchar are competing for the same voters, and with both rising in polls and in prominence, the gloves have come off.
The growing animosity between the two, however, could threaten both of their candidacies, experts told NBC News, especially if it spills over onto Wednesday's debate stage.
"The bet is that by going negative, some voters will join their teams, but with so many moderates still running, the safer bet is that it could chase people away," said Michael Trujillo, a veteran Democratic strategist based in Los Angeles.
"They obviously need to contrast themselves with one another and other folks on stage, so it makes sense for them to do this, but I'm not sure it helps," added Trujillo, who is not affiliated with any candidate or outside groups this election cycle.
Klobuchar, a senator from Minnesota, turned heads at a Democratic debate this month by repeatedly knocking Buttigieg, the former mayor of South Bend, Indiana, for his relative lack of experience and using an aside he'd made weeks earlier against him. (At a campaign event in Iowa, he said he was so turned off by the impeachment goings-on in Washington that he wanted to "switch it off and just watch cartoons or something.")
"It is easy to go after Washington because that's a popular thing to do," Klobuchar said, adding that it makes "you look like a cool newcomer."
"I don't think that's what people want right now. We have a newcomer in the White House, and look where it got us. I think having some experience is a good thing," she said. Later, in her closing remarks, Klobuchar pitched herself as "not a political newcomer with no record."
Buttigieg has been returning fire — directly and indirectly — on the trail in the days since.
At an event Thursday in Las Vegas, Buttigieg swiped at Klobuchar for voting to confirm Trump's pick for Customs and Border Protection commissioner.
"I've heard some people say that, you know, my experience is not relevant because you have to have Washington experience in order to become a president," Buttigieg said. "But some of those same voices are among those who voted to confirm Kevin McAleenan as the CBP head, who presided over, for example, the horrifying conditions that children were kept in, and we have to look at what kind of judgment that experience has brought."
At an event in California the next day, he mocked Klobuchar for not being able to recall the name of the president of Mexico when asked at an event in Nevada. Buttigieg, who was at the same event, easily rattled off the name: Andrés Manuel López Obrador.
Buttigieg and Klobuchar will have every opportunity to reprise those attacks, and introduce new ones, at the the debate Wednesday night in Las Vegas.
"It's really the only major opportunity for them to have so many eyeballs looking at them," Trujillo said. "Nobody is going to be watching the caucus results come in on Saturday. Nobody is watching CNN or MSNBC at 4 p.m. on a Saturday to see who they're going to vote for in their own primary race. They're at soccer practice with their kids."
"The debate is the big moment," he said.
Spokespersons for the Buttigieg and Klobuchar campaigns declined to comment.
But leaning into the attacks doesn't come without major risks, said Jon Ralston, a veteran Nevada journalist who runs The Nevada Independent.
By forcefully attacking Klobuchar, Buttigieg risks sullying the positive and inspiring message of his surging presidential campaign. And now that Klobuchar finally has people's attention — she announced her campaign more than a year ago but has begun receiving serious notice only after her strong finish in the New Hampshire primary — voters may be turned off by how critical she's being of one of her main competitors.
"While Klobuchar has been around a lot longer, a lot of voters still don't know her. The debate will be an opportunity for them to meet her. They may come in thinking she's 'Minnesota Nice,'" said Ralston, who is one of the debate's moderators. "But this could change that."
Ralston said, however, that "if Pete fully goes negative," it "could hurt him."
On the other hand, said Tracy Sefl, a Democratic strategist who worked for Hillary Clinton's campaigns in 2008 and 2016 but is not affiliated with any campaign or outside groups this time around, a bit of nastiness may be necessary from Buttigieg and Klobuchar to reassure voters that they can go hard after President Donald Trump, who is no stranger to mudslinging.
"We need to dispense with the notion that Midwesterners aren't capable of taking shots," Sefl, an Iowa native, told NBC News.
"She's taken her shots at Pete, and they've been pretty effective. She's chosen her spots to attack, and those particular attacks have been really effective," said Sefl, who also pointed out that Klobuchar "got a nice little bump" after her previous debate performance, when she went hard after Buttigieg.
But, Ralston warned, it might not matter whose attacks land better. If Buttigieg and Klobuchar continue bruising each other, it's only likely to benefit someone else entirely: progressive Sen. Bernie Sanders, I-Vt.
"The competition now is for the non-Bernie candidate," he said. "At the moment, it's Bernie and the rest of the field."