Sen. Amy Klobuchar went into Tuesday night's Democratic presidential debate facing the very real prospect it could be her last and turned in her most aggressive performance to date with repeated jabs at a leading rival.

"The difference between a plan and a pipe dream is something you can actually get done," Klobuchar said to Sen. Elizabeth Warren toward the end of a spirited back-and-forth over Medicare for All, which Warren supports and Klobuchar does not.

Over three previous Democratic debates, Klobuchar rarely attacked her Democratic rivals head-on. But the stakes are rising, Klobuchar remains stalled at low single digits in the polls, and she has not yet qualified for the next Democratic debate in November. Her predicament set the stage for several runs at the Massachusetts senator, who has been leading the Democratic race in recent polls.

"At least Bernie [Sanders] is being honest," Klobuchar said to Warren, after she didn't directly answer whether tax increases would be needed to implement Medicare for All. "Elizabeth, you have not said that," Klobuchar said, addressing Warren.

Warren insisted her health insurance plan would not raise costs on the middle class. Klobuchar, citing the estimated 149 million Americans who would be moved off private plans under Medicare for All, continued her attack: "You're making Republican talking points right now in this room."

Instead of pursuing such a wholesale change, Klobuchar said, the next Democratic president should push for a public option in health care and push prescription drug companies to lower their costs.

That wasn't the only time Klobuchar suggested more left-leaning proposals from some Democratic rivals could hurt the party's electoral prospects. Commenting on former congressman Beto O'Rourke's call for mandatory gun buybacks, Klobuchar said the public is with Democrats on more modest gun-control proposals but perhaps not ready for more sweeping restrictions like buybacks.

"Let's not mess this up with this fight," Klobuchar said.

In her first chance to speak in Tuesday night's 12-candidate melee in Ohio, Klobuchar offered a withering critique of President Donald Trump, saying he deserves to be impeached. She was also first of the 12 on stage to slam Trump for his recent move to pull U.S. troops out of Syria.

"Calling Ukraine for political dirt doesn't make America great again," Klobuchar said. "Leaving the Kurds for slaughter doesn't make America great again. Coddling up to Vladimir Putin doesn't make America great again. It makes Russia great again."

The first skirmish over Medicare for All was not the only time Klobuchar sought a confrontation with Warren.

"I want to give a reality check to Elizabeth — your idea is not the only idea," Klobuchar said during a discussion of Warren's proposed wealth tax. "It is not one idea that rules here."

Klobuchar said she's not opposed to more taxes on the wealthy. "No one on this stage wants to protect billionaires," she said, mentioning her proposal to repeal major portions of the Republican tax cuts that benefited the rich and corporations.

Failing to qualify for past debates was a death knell for the campaigns of several contenders now gone from the race, a fate awaiting Klobuchar if her poll numbers don't improve.

For the Nov. 20 debate in Georgia, candidates have until Nov. 13 to accrue 165,000 individual donors and reach at least 3% in four national polls (or 5% in two polls of early nominating states).

Klobuchar has already passed the donor threshold for November, but her campaign said so far she only has one of the polls she needs. As of Tuesday, she was at 1.6% in Real Clear Politics' running average of national polls of the Democratic race.