US President Joe Biden is facing increasing calls from within his own party to step aside from his re-election bid, with frustrations among congressional Democrats reaching a boiling point.

According to reports from Axios, several House Democrats have indicated a significant shift in sentiment, with one member noting, "The dam is breaking."

Another expressed that Biden should "step down and help lead a transition of candidacy," echoing a sentiment shared by a "very large majority" of the caucus.

The push for Biden to withdraw comes amidst concerns over his recent debate performance and the handling of campaign fallout, including dismissive responses to questions about his age and leadership.

A draft letter urging Biden's withdrawal is reportedly circulating among lawmakers, with one Democrat saying it is "all anyone is talking about."

House Minority Leader Hakeem Jeffries has been actively gauging member sentiment, with newer Democrats from swing districts reportedly expressing reluctance to continue supporting Biden.

Sources familiar with discussions indicate that Vice President Kamala Harris has emerged as a favored replacement candidate among some members.

Read more: Democrat vs. White House saga over Biden's future as president ongoing

Despite these growing calls for change, support for Biden remains mixed within the party. Leaders like Jeffries and Senate Majority Leader Chuck Schumer have publicly affirmed their backing for the president, while some members of the Congressional Black Caucus argue for maintaining unity around Biden.

In response to the internal dissent, the Biden campaign boasted about strong fundraising and cited polls showing a competitive race against former President Donald Trump.

A memo circulated among congressional Democrats detailed Biden's forthcoming interview with ABC News as part of ongoing efforts to bolster his candidacy.

House Democratic leaders are set to discuss the situation in an upcoming call on Wednesday afternoon, with Hakeen playing a pivotal role in the discussion.

"Hakeem is the key," said one House Democrat. "When you start seeing signals from him, I think the whole herd will follow quickly."

Read more: Democrat lawmaker calls on Biden to withdraw from presidential race