United States President Joe Biden is battling to save his re-election campaign as concerns about his age and fitness fuel doubts about his ability to beat Republican challenger Donald Trump.

During a high-stakes news conference on Thursday, Biden, 81, struck a defiant tone, insisting he is the most qualified person to beat Trump, and that he will not quit the race.

“I’ve gotta finish this job because there’s so much at stake,” Biden said.

While Biden delivered a coherent defence of his administration’s record at home and overseas, the president also made a number of stumbles, including mistakenly referring to Vice President Kamala Harris as “Vice President Trump”.

After Biden’s latest appearance, three more elected Democrats joined the growing list of allies calling on the president to step aside, although the bulk of his party has – publicly, at least – stood behind his candidacy.

Here is a list of Biden allies who have called on the president to stand down:

House Democrats

So far, 17 Democrats in the House of Representatives have called on Biden to bow out.

Eric Sorensen of Illinois on Thursday night became the third House Democrat to call on Biden to withdraw after he wrapped up his news conference, following Jim Himes of Connecticut and Scott Peters of California.

“In 2020, Joe Biden ran for President with the purpose of putting country over party. Today, I am asking him to do that again. It is more important than ever that our neighbours have a candidate for President who will communicate a positive vision for every person in this country,” Sorensen said in a statement.

Texas Representative Lloyd Doggett was the first House Democrat to publicly call for a new nominee on July 2, saying, “Too much is at stake to risk a Trump victory.”

The other House Democrats who have publicly called on Biden to drop out are: Marie Gluesenkamp Perez (Washington); Greg Stanton (Arizona); Raul Grijalva (Texas);  Mike Quigley (Illinois); Angie Craig (Minnesota); Adam Smith (Washington); Mikie Sherrill (New Jersey); Seth Moulton (Massachusetts); Pat Ryan (New York); Earl Blumenauer, (Oregon); Hillary Scholten (Michigan); Brad Schneider (Illinois); and  Ed Case (Hawaii).

Senate Democrats

Senator Peter Welch of Vermont on Wednesday became the first – and so far only – US senator to publicly call for Biden to step aside, saying doing so would be for the “good of the country”.

Numerous other Senate Democrats, however, have voiced concerns about the likelihood of a Trump victory, including Michael Bennet of Colorado, Richard Blumenthal of Connecticut, Patty Murray of Washington, Raphael Warnock of Georgia, and Tim Kaine of Virginia.

Congressional Leadership

Senate Majority Leader Chuck Schumer of New York has backed Biden in public, but some US media outlets have reported that his support may be wavering. Schumer’s colleague Nancy Pelosi, the former Speaker of the House, this week declined to definitively back Biden’s candidacy in a television interview, saying he should make a decision about continuing in the race soon, even though the president has repeatedly insisted he will not drop out.

Democrat Governors

No Democratic governors have so far called on Biden to step aside.

However, a number of them, including Michigan’s Gretchen Whitmer, Illinois’ JB Pritzker and Maura Healey of Massachusetts, have raised concerns about Biden’s health and competitiveness.

New York Lieutenant Governor Antonio Delgado on Wednesday became the first deputy leader at the state level to call on Biden to step down.

Democrat Donors

Biden has lost the support of a number of major party donors, including Disney heiress Abigail Disney, Hollywood producer Damon Lindelof, and philanthropist Gideon Stein, all of whom have said they will withhold funds until he steps aside.

Netflix co-founder Reed Hastings and Los Angeles real estate mogul Rick Caruso, both of whom are known as major contributors to the Democrats, have also called on the president to bow out.

Celebrities

In a guest essay in The New York Times on Wednesday, George Clooney, a longtime Democratic donor, called on Biden to drop out, saying he had witnessed the president’s decline firsthand at a major fundraiser he co-hosted last month.

Other celebrities who have called on Biden to go include acclaimed horror author Stephen King, director Michael Moore, actor and filmmaker Rob Reiner, actor John Cusack and TV host Sara Haines.

While stopping short of saying Biden should quit, late-night TV host Jon Stewart has said it is important to “open up the conversation”.