Trump’s comments came after he was asked during the debate at Hofstra University in New York how he plans to address racial tensions as president. The moderator, NBC News’ Lester Holt, specifically questioned how Trump plans to do this in light of the fact he promoted theories alleging Obama was born in Kenya.

The GOP nominee responded by saying it was Clinton who first questioned the president’s identity. The Democratic nominee, for her part, denied Trump’s charge while also attacking him for engaging in so-called birtherism.

“It can’t be dismissed that easily,” Clinton said. “[Trump] really started his political activity based on this racist lie that our first black president was not an American citizen.”

Clinton and her team have focused recently on Trump’s embracing of “birtherism,” arguing at length that conspiracies alleging the president was born in Kenya are motivated entirely by bigotry and flat-out racism.

“For five years, [Trump] has led the ‘birther’ movement to delegitimize our first black president,” Clinton said earlier this month at an address at the Black Women’s Agenda 39th Annual Symposium. “His campaign was founded on this outrageous lie. There is no erasing it in history. Barack Obama was born in America, plain and simple. And Donald Trump owes him and the American people an apology.

“Donald Trump looks at President Obama after eight years as our president. He still doesn’t see him as an American. Think of how dangerous that is. Imagine a person in the Oval Office who traffics in conspiracy theories and refuses to let them go no matter what the facts are,” she said.

Trump backed away from his embrace of birtherism during an address this month at his new hotel in Washington, D.C., and stated that he believes Obama was born in the United States.

However, the Clinton campaign said Trump’s attempt to disown the issue isn’t good enough, and the Democratic nominee and her team have kept after it at nearly every opportunity.

“We are not going to let him move on to the next issue,” Democratic vice presidential candidate Sen. Tim Kaine, D-Va., said on Sept. 19 at a campaign rally in Ames, Iowa. “This is not just a wacky guy saying wacky stuff. This is incredibly painful to millions of people.”

“When Donald Trump decides about the first African-American president of this country, to repeatedly go after him and say, ‘You are not a citizen of the United States,’ he’s basically hauling us back to the most painful chapter in the life of this nation,” Kaine said.

“Why would someone like Donald Trump want to drag us back to that painful chapter in in American life, when if you were African-American you couldn’t be a citizen?” the Virginia senator asked.

Trump was asked later why he flipped on his previous enthusiasm for birtherism, to which he responded, “Well I just wanted to get on with, I wanted to get on with the campaign. A lot of people were asking me questions.”

Clinton has made race a major issue in her campaign, and has responded to recent events surrounding police action in minority communities by saying Americans need to do more to address racial inequality.

“We have got to tackle systemic racism,” Clinton said earlier this month in a radio interview. “This is just unbearable and it needs to be intolerable.”

On Monday, she repeated her call to address racial inequality in the United States.

“[W]e’ve got to address the systemic racism in our criminal justice system,” she said during the presidential debate. “We can’t just say law and order. We have to say, we have to come forward with a plan that is going to divert people from the criminal justice system.”

“Deal with mandatory minimum sentences, which have put too many people away for too long for doing too little,” she said. “We need more second chance programs. … There are some positive ways we can work on this.”