President Joe Biden‘s campaign insisted Friday that he will remain at the top of the Democratic ticket, stressing in a new memo that Biden still has the support of voters, even as a growing number of Democratic lawmakers call on him to drop out.

“While voters consistently mention President Biden’s age when contacted, our target voters — both reengagement and true swing voters — are still planning to vote for him, making it clear the debate has not hurt support among the voters who will decide this election,” says the memo, first reported by NBC News.

“Joe Biden has made it more than clear: he’s in this race and he’s in it to win it. Moreover, he’s the presumptive nominee, there is no plan for an alternative nominee,” the memo said.

More than a dozen Democrats in Congress publicly called on Biden to drop his reelection bid on Friday, bringing the total number to more 30.

“In a few short weeks, Joe Biden will be the official nominee. It is high past time we stop fighting one another,” the Kanninen memo said. “The only person who wins when we fight is Donald Trump.”

But Kanninen acknowledged that many polls show Biden trailing Trump, writing, “I will not sugar coat the state of the race: we have our work cut out for us to win this November.”

Biden, who on Wednesday tested positive for Covid-19, is currently self-isolating in Rehoboth, Delaware.

Biden campaign chair Jen O’Malley Dillon said on MSNBC’s “Morning Joe” Friday that the president will be back on the campaign trail next week.