Sen. Elizabeth Warren and Mayor Pete Buttigieg battled during the Democrat debate on Thursday about the billionaires who support the South Bend Mayor’s campaign.

Warren immediately attacked Buttigieg’s recent fundraiser in Napa Valley, California, in a wine cave full of crystals and $900 bottles of wine.

“We made the decision many years ago that rich people in smoked filled rooms would not pick the next president of the United States, billionaires in wine caves should not pick the president of the United States,” she said during the Politico/PBS Democrat presidential debate on Thursday night.

Buttigieg replied by noting that Forbes magazine said that he was the only candidate who was not a millionaire or a billionaire.

“This is the problem with issuing purity tests you cannot yourself pass,” Buttigieg said, earning a strong reaction from the crowd.

He argued that if he refused to meet with millionaires and billionaires, he could not be on the debate stage with the rest of the Democrat field.

Buttigieg said that Warren’s net worth was “100 times” that of his own, and said that if she ever donated to his campaign he would be glad to have the support.

“We need the support of everybody who is committed to defeat Donald Trump,” Buttigieg replied.

Warren replied that she did not “sell access to her time” and did not host closed-door fundraisers with billionaires, and added that she would not offer ambassador spots to her donors.

“If you cannot stand up to the wealthy and well connected when you are a candidate then how can the American people believe that you’re going to stand up to the wealthy and the well connected when you are president and it’s really hard,” Warren said.

Buttigieg argued that Warren had transferred funding from wealthy donors into her campaign coffers.

“Did it corrupt you, Senator? Of course not,” Buttigieg said.

Buttigieg argued that former President Barack Obama and House Speaker Nancy Pelosi continued to do fundraisers with wealthy people without getting corrupted.

“These purity tests shrink the stakes of the most important election of our time,” he said.