Lloyd Doggett has become the first Democratic politician to publicly call on US President Joe Biden to withdraw from the race for the White House.
It comes after Mr Biden's poor performance in the opening presidential debate against Republican candidate Donald Trump last week.
"Recognising that, unlike Trump, President Biden's first commitment has always been to our country, not himself, I am hopeful that he will make the painful and difficult decision to withdraw. I respectfully call on him to do so," the Texas Congressman said in a statement.
Some Democrats loyal to Joe Biden have raised fresh questions about his 2024 re-election bid, a shift after many defended him after last week's shaky debate performance.
Former House Speaker Nancy Pelosi emphasized Biden's multiple legislative accomplishments during an interview with MSNBC on Tuesday but said it was a legitimate question to ask whether his debate performance was a one-night thing or a broader health problem. She said Trump should be given the same scrutiny.
"I think it's a legitimate question to say, 'is this an episode or is this a condition?' And so when people ask that question, it's legitimate, of both candidates," Ms Pelosi said.
"He has to be honest with himself," Democratic Representative Mike Quigley, a moderate from Illinois, told CNN.
"It's his decision. I just want him to appreciate at this time just how much it impacts, not just his race, but all the other races coming in November," he said.
Democratic Senator Sheldon Whitehouse also asked for reassurances, saying voters needed to know there would be no repeat of Mr Biden's sub-par showing.
Mr Whitehouse, of Rhode Island, told WPRI-TV he was "pretty horrified" by the president's performance during the 90-minute CNN match-up, watched by more than 50 million Americans.
Mr Biden will hold a meeting with Democratic governors tomorrow and speak to politicians this week, White House officials said, in the wake of his poorly received debate with Republican presidential candidate Donald Trump.
The meeting, which will be held at the White House but may be largely virtual with governors attending remotely, will give the president a chance to reassure leaders in his party that he is of sound mind and body despite the debate, which prompted calls for him to step aside as the Democratic Party's presidential nominee.
One official said Mr Biden would also meet with leaders from Capitol Hill this week as he seeks to shore up support among party stalwarts and tamp down talk that he should step aside.
The meetings are part of a broad effort to stabilize the president's re-election bid after his halting, stumbling display on the Atlanta debate stage.
His team held difficult phone calls on Sunday and yesterday with important campaign funders who questioned whether the 81-year-old Democrat should stay in the presidential race.
