New York - New York City Mayor Bill de Blasio on Wednesday called on his Democratic presidential rival, former Vice President Joe Biden, to apologize for remarks he made on Tuesday about his time working civilly with white supremacists serving in the Senate in the 1970s.

“It’s past time for apologies or evolution from @JoeBiden,” de Blasio wrote on Twitter. “He repeatedly demonstrates that he is out of step with the values of the modern Democratic Party.”

Biden’s campaign did not immediately respond to a request for reaction to de Blasio’s comments.

Biden, 76, and de Blasio, 58, are two of 24 candidates vying for the Democratic nomination to challenge Republican President Donald Trump in 2020. Biden is currently the front runner in early polls. De Blasio has struggled to garner much support.

At issue for de Blasio are Biden’s remarks at a New York City fundraiser for his presidential campaign on Tuesday night.

Biden said that U.S. leaders have lost the ability to work together. He pointed to two segregationists from the South who were serving in the Senate when Biden was elected - Democratic Senators James Eastland of Mississippi and Herman Talmadge of Georgia.

Eastland was a vocal white supremacist who described black people as inferior and fought against efforts to desegregate the South. When Biden joined the U.S. Senate in 1973, he and Eastland, members of the same political party, served on the same committee.

“At least there was some civility. We got things done. We didn’t agree on much of anything. We got things done. We got it finished,” Biden said, according to a pool report distributed by his campaign. “But today, you look at the other side and you’re the enemy. Not the opposition, the enemy. We don’t talk to each other anymore.” Read more at Reuters