US Democratic presidential candidate Joe Biden said on Wednesday that Donald Trump is the first racist to become president in remarks his opponent’s re-election campaign quickly rebuked.

Biden, who was vice president under Barack Obama, the first Black US president, fielded a question at a Service Employees International Union roundtable from a healthcare worker concerned about the Republican president calling the coronavirus pandemic the “China virus.”

He responded by saying it was “absolutely sickening” how Trump “deals with people based on the color of their skin, their national origin, where they’re from.”

“No sitting president’s ever done this. Never, never, never. No Republican president has done this”, the former vice president said.

In response to that, Trump campaign senior adviser Katrina Pierson called Biden’s comments “an insult to the intelligence of Black voters” given the onetime senator’s past work with segregationist lawmakers. She said Trump “loves all people” and “works hard to empower all Americans.”

Race became an even more central issue as protests raged over unarmed African Americans being killed by police in the aftermath of the May death of George Floyd, a Black man who died after a white Minneapolis police office pressed his neck into the pavement for more than eight minutes.

Biden has effectively been his party’s leader since his last challenger in the Democratic primary, Bernie Sanders, ended his campaign in April.

In May, Biden and the Democratic Party raised nearly $81 million, 10 percent more than Trump, although the president has more overall campaign cash.

Biden is currently leading in national polling, as well as in surveys conducted in several swing states like Michigan, Wisconsin and Pennsylvania, battlegrounds that were critical to Trump’s victory in 2016.

The 2020 US presidential election is scheduled for Tuesday, November 3.