Amy Klobuchar raised her hand. Then she raised the tension in her budding rivalry with Pete Buttigieg.

“When we were in the last debate, Mayor, you basically mocked the hundred years of experience on the stage,” the third-term senator from Minnesota, 59 years old, said to the 37-year-old mayor of South Bend, Ind. She pointed out to the other two senators on the stage, as well as former vice president Joe Biden.

“ … So while you can dismiss committee hearings, I think this experience works,” Klobuchar said. “I have not denigrated your experience as a local official. I have been one. I just think you should respect our experience when you look at how you evaluate someone who can get things done.”

Klobuchar looked for — and found — opportunities to take aim at Buttigieg during the Democratic debate Thursday night, challenging the youngest candidate in the field about his relative lack of experience and his arguments against Washington insiders. Buttigieg responded forcefully each time, defending his experiences and his ability to attract voters.

Sen. Elizabeth Warren (D-Mass.) also tangled with Buttigieg, but Klobuchar remained his most dedicated adversary throughout the night. Their confrontations reflect the increased stakes they face in Iowa, where both Midwesterners are pitching themselves as the younger, moderate alternative to Biden — and where both have seen their poll numbers rise in recent months. Buttigieg is essentially tied with Biden, Warren and Sen. Bernie Sanders (I-Vt.) in that contest, according to a Washington Post average of polls.

Klobuchar began her aggressiveness toward Buttigieg before Thursday, when their simmering feud escalated on the national stage. She was the first female candidate to wonder out loud to reporters whether the young mayor would be on the debate stage at all if he were a woman.

“Could we be running with less experience than we had?” Klobuchar asked in an interview with the New York Times in November. “I don’t think people would take us seriously.”

She built on those comments when asked about them in last month’s debate.

“What I said was true. Women are held to a higher standard,” she said then. “Otherwise we could play a game called ‘Name Your Favorite Woman President,’ which we can’t do because it has all been men, including all vice presidents being men. And I think any working woman out there, any woman that’s at home, knows exactly what I mean.”

On Thursday, Klobuchar didn’t wait for an invitation to challenge Buttigieg. Buttigieg was winding through a condemnation of President Trump’s attacks on the free press and First Amendment when Klobuchar raised her hand. She didn’t seem to disagree with Buttigieg. But she wanted to draw a distinction anyway.

“I just want to make very clear, Mayor, that the freedom of the press is deep in my heart. My dad was a newspaper man,” Klobuchar said, before explaining that she asked both of Trump’s attorneys general during confirmation hearings whether they would protect journalists. “So this is not just talking points to me. This is the real world. I think that experience that I will bring to the White House with protecting the First Amendment is worth more than any talking points.”

Later, Buttigieg told Klobuchar she did, in fact, denigrate his experience in previous comments. Buttigieg, who served in Afghanistan, mentioned his time in the Naval Reserve as evidence of his commitment to defending the First Amendment and the Constitution.

“You seemed to imply that our relationship to the First Amendment was a talking point, as if anyone up here has any more or less commitment to the Constitution than anybody else up here,” Buttigieg said. “Let me tell you about my relationship to the First Amendment. It is part of the Constitution that I raised my right hand and swore to defend with my life. That is my experience. And it may not be the same as yours, but it counts. Senator, it counts.”

Later, after Buttigieg was asked whether he supports reparations for descendants of slaves, Klobuchar pivoted to something he had said earlier, about immigration, to attack him again. Buttigieg suggested that immigration reform had been needed for decades, but that Washington institutions had not been able to deliver it.

Klobuchar continued her assault, this time targeting his ability to win elections beyond the local level. Buttigieg fired back, arguing that while his vote totals might not be as big as those in statewide elections, “try putting together a coalition to bring you back to office with 80 percent of the vote as a gay dude in Mike Pence’s Indiana.”

Shortly after coming out publicly for the first time, Buttigieg won reelection as South Bend mayor by a wide margin. Klobuchar wanted to talk about his failed bid in 2010 for state treasurer instead.

“If you had won in Indiana, that would be one thing,” Klobuchar said. “You tried and you lost by 20 points.”

Buttigieg also slipped into a back-and-forth with Warren — a conflict that seemed inevitable after they spent weeks arguing through the media about their relative transparency and fundraising purity standards. Warren called out Buttigieg for hosting a fundraiser in a “wine cave” with crystal chandeliers.

“Billionaires in wine caves should not pick the next president of the United States,” Warren said.

Buttigieg responded with an argument he has used repeatedly as Warren has targeted him in recent weeks: He reminded the audience that Warren used to hold closed-door, big-dollar fundraisers, too — and that a large portion of her campaign’s funds rolled over from her Senate campaign, before she pledged not to hold them anymore.

“This is the problem with issuing purity tests you cannot yourself pass,” said Buttigieg, who argued that House Speaker Nancy Pelosi (D-Calif.) and former president Barack Obama both fundraised like he does.

Those exchanges marked some of the more heated of the evening, a reflection of Warren’s and Klobuchar’s need to combat Buttigieg’s rise in the polls in early voting states. Like Buttigieg, Klobuchar is banking on a strong Iowa showing to solidify her case for the nomination. Like Klobuchar, Buttigieg is playing up his Midwestern roots and the need for pragmatism. To get where each wants to go, they are in each other’s way.