Biden says he’s returning to campaign trail next week as calls grow for him to step aside

President Joe Biden said on Friday that he would be returning to the campaign trail next week to continue to take on rival Donald Trump, as he contends with the fallout from his COVID-19 diagnosis and growing calls from Democrats for him to bow out, including from Ohio Sen, Sherrod Brown on Friday evening, the fourth senator to do so.

"I look forward to getting back on the campaign trail next week to continue exposing the threat of Donald Trump's Project 2025 agenda while making the case for my own record and the vision that I have for America: one where we save our democracy, protect our rights and freedoms, and create opportunity for everyone," Biden said in a statement.

"The stakes are high, and the choice is clear," Biden added. "Together, we will win."

The president also criticized Trump's Thursday night keynote speech at the Republican National Convention, saying the former president "focused on his own grievances, with no plan to unite us and no plan to make life better for working people."

"Last night the American people saw the same Donald Trump they rejected four years ago," Biden wrote.

Biden has been sidelined since Wednesday when he was diagnosed with COVID-19 moments before delivering remarks in Las Vegas at the UnidosUS conference, the largest Latino civil rights group in the country. He abruptly cut his trip short and flew to his beach home in Rehoboth Beach, Del.

Boarding Air Force One Wednesday, Biden struggled to walk up the shorter stairs that pull out from under the plane. And after arriving in Dover, he again struggled deplaning, and Secret Service appeared to physically help him into the waiting SUV.

But Biden's determination to return to the campaign trail appears to be because his team is reenergized by Trump's speech.

"He's playing the greatest hits from 2016 - Trump has not changed, he has not moderated, he has gotten worse," a Biden adviser said Thursday night. "And he is making no appeal to moderates."

The president said Trump laid out a "dark vision" for America's future and that "Together, as a party and as a country, we can and will defeat him at the ballot box."

But his party is not together. Democrats remain split on whether Biden can beat Trump in November and on Friday at least 10 Democrats joined the chorus calling on Biden to resign, including Texas Rep. Marc Veasey, the first member from the influential Congressional Black Caucus to do so.

"Mr. President, with great admiration for you personally, sincere respect for your decades of public service and patriotic leadership, and deep appreciation for everything we have accomplished together during your presidency, it is now time for you to pass the torch to a new generation of Democratic leaders," Veasey co-wrote in a letter with Reps. Jared Huffman, Chuy Garcia, and Mark Pocan.

"We must defeat Donald Trump to save our democracy… At this point, however, we must face the reality that widespread public concerns about your age and fitness are jeopardizing what should be a winning campaign," the four congressmen added.

Brown, in a close reelection fight, said in a statement that many Ohioans had contacted him.

"Over the last few weeks, I've heard from Ohioans on important issues, such as how to continue to grow jobs in our state, give law enforcement the resources to crack down on fentanyl, protect Social Security and Medicare from cuts, and prevent the ongoing efforts to impose a national abortion ban. These are the issues Ohioans care about and it is my job to keep fighting for them," he said.

“I agree with the many Ohioans who have reached out to me. At this critical time, our full attention must return to these important issues. I think the President should end his campaign," he said.

Democratic Sen. Martin Heinrich of New Mexico and Democratic Rep. Greg Landsman, who represents a battleground Ohio district, both also pointed to Trump and the risk to "democracy" for reasons Biden should exit.

"There is too much on the line, and we have to be able to make that case to the American people about the change we need and the country we all deserve," Landsman wrote in his statement. "After weeks of consideration and hundreds of conversations with constituents, I have come to the conclusion that Joe Biden is no longer the best person to make that case."

Rep. Zoe Lofgren of California, a close ally of former Speaker Nancy Pelosi, in a letter addressed to the president on Thursday, but was first reported on Friday, made a similar argument doubting Biden can effectively run a winning campaign.

"I want to be clear that should you formally become the Democratic nominee for President I will do everything I can to promote your candidacy and to work for your success," Lofgren wrote in the letter obtained by ABC News. "Unfortunately, I greatly doubt that the outcome will be positive, and our country will pay a dreadful price for that."

Biden campaign chair Jen O'Malley Dillon admitted on MSNBC's "Morning Joe" Friday that they have seen Biden's support slip.

"I'm not here to say that this hasn't been a tough several weeks for the campaign," O'Malley Dillon said. "There's no doubt that it has been, and we've definitely seen some slippage in support, but it has been a small movement, and you know this, the reason is because so much of this race is hardened already."

In what was a bruising day for the president, with the calls from congressional Democrats urging him to drop out swelling to 34 by ABC News's count, Biden did get critical support from the Congressional Hispanic Caucus.

The group's political arm, BOLD PAC, on Friday endorsed the president, a week after his call with the group, saying he and Vice President Kamala Harris "have delivered for the Latino community."

Amid news of more congressional Democrats on Friday joining calls for Biden to step aside, his campaign said it recognizes that the "urgency" of beating Donald Trump has led some Democrats to publicly abandon their support of the president leading the ticket -- though they remain confident the party will unite by November.

"While the majority of the caucus and the diverse base of the party continues to stand with the President and his historic record of delivering for their communities, we're clear-eyed that the urgency and stakes of beating Donald Trump means others feel differently," Biden campaign spokesperson Mia Ehrenberg said in a statement to ABC News.

"We all share the same goal: an America where everyone gets a fair shot and freedom and democracy are protected," Ehrenberg added. "Unlike Republicans, we're a party that accepts – and even celebrates – differing opinions, but in the end, we will absolutely come together to beat Donald Trump this November."