A series of polls released a week after the fourth Democratic presidential primary debate in Ohio show former Vice President Joe Biden back on top as the frontrunner while Massachusetts Senator Elizabeth Warren begins to fall behind.

Biden, who, according to a Real Clear Politics’ aggregate of polls was briefly eclipsed by Warren as the frontrunner in the days leading up to the debate has regained his lead as opponents shifted their criticisms to Warren.

Biden now leads the crowded primary field with nearly 29 percent support while Warren now garners 23 percent. Vermont Senator Bernie Sanders maintains his third place standing with just more than 16 percent and everyone else remains in single digits.

In Iowa however, Biden and Warren remain neck and neck, with Biden at 21 percent and Warren just 0.3 points behind at 20.7 percent according to Real Clear Politics’ aggregate with the polls showing a statistical tie between the two in the critical first-in-the-nation caucus state. South Bend, Indiana Mayor Pete Buttigieg meanwhile, is surging in the Hawkeye state surpassing Sanders for third place in the two most recent polls conducted. Buttigieg is now tied with Sanders in Real Clear’s aggregate.

Warren is also maintaining her lead in New Hampshire, leading Biden with little more than 27 percent support to Biden’s 24 percent and Sanders coming behind in less than 17 percent in Real Clear Politics’ New Hampshire aggregate, though no polls have been conducted in the state following last week’s debate.

The recent update in poll standings come after Warren took fire from all around the stage in Ohio earlier this month as her Democratic White House rivals lobbed attacks at the candidate who has been characterized as the candidate with a plan for everything but failure to have a way to pay for her signature healthcare plan Medicare for All.

“Your signature, senator, is to have a plan for everything, except this. No plan has been laid out to explain how a multi-trillion dollar hole in this ‘Medicare for All’ plan,” Buttigieg charged on stage.

Warren was asked repeatedly whether she would raise middle class taxes to fund her plan for Medicare for All but dodged the question multiple times throughout the night from moderators and opponents.

“I appreciate Elizabeth’s work. But again, the difference between a plan and a pipe dream is something you can actually get done,” Senator Amy Klobuchar of Minnesota said.

Senator Sanders, whose plan Warren based her own on, readily admitted to the need to raise taxes on the middle class in order to pay for the prohibitively expensive proposal.

“I do think it is appropriate to acknowledge that taxes will go up,” Sanders said.

A new study released Tuesday from the Committee for a Responsible Federal Budget, an independent public policy think tank based in Washington D.C. concluded it is mathematically impossible to fund Medicare for All without a middle class tax hike.