STORY: Calls for Joe Biden to step aside as the Democratic candidate in the 2024 presidential election continue to grow from within his own party.

:: File

On Wednesday, U.S. Representative Adam Schiff of California became the 20th Congressional Democrat to suggest Biden end his reelection bid against Republican challenger Donald Trump.

That's according the Los Angeles Times, which quoted Schiff saying: "A second Trump presidency will undermine the very foundation of our democracy, and I have serious concerns about whether the President can defeat Donald Trump in November."

Democratic concern about the 81-year-old incumbent's ability to beat Trump surged after Biden's halting debate performance on June 27.

But Biden has so far stood firm. At an NAACP rally in Las Vegas this week, he told the crowd he was "all in."

:: July 16, 2024

"Freedom, democracy, America always marching, always believing, always keeping the faith. We're going to do this. So they ask you, are you all in? (AUDIENCE RESPONDS: All in.) Because I'm all in."

Biden was greeted by chants of "four more years" as he spoke to the major gathering of Black voters.

Tracey Presley is an NAACP delegate from the crucial swing state Wisconsin.

"So my feelings after seeing him speak today is he is definitely strong, he's definitely ready to do the job and he understands the assignment. And I don't believe it is the time for him to step down right now."

:: January 23, 2020

But Schiff's voice could be particularly resonant: The California Democrat is a prominent Trump critic who headed the 2019 investigation that led to Trump's first impeachment over his alleged effort to pressure Ukraine to help him win re-election.

Trump remained in office because the Senate declined to convict him.

Schiff is currently campaigning for the U.S. Senate.

Some Democratic lawmakers have voiced concern that Biden staying in the race could hurt the party in down-ballot races.