Leading House Democrat Adam Smith calls on Biden to end presidential bid

Joe Biden’s position among congressional Democrats eroded further on Monday when an influential House committee member lent his voice to calls for him to end his presidential campaign following last month’s spectacular debate failure.

Adam Smith, the ranking Democrat on the armed services committee in the House of Representatives, issued the plea just hours after the president emphatically rejected calls for him to step aside in a letter to the party’s congressional contingent.

Biden had also expressed determination to continue in an unscheduled phone interview with the MSNBC politics show Morning Joe.

But in a clear sign such messaging may be falling on deaf ears, Smith suggested that sentiments of voters that he was too old to be an effective candidate and then president for the next four years was clear from opinion polls.

Related: The Democrats who have called on Joe Biden to step down

“The president’s performance in the debate was alarming to watch and the American people have made it clear they no longer see him as a credible candidate to serve four more years as president,” Smith, a congressman from Washington state, said in a statement.

“Since the debate, the president has not seriously addressed these concerns.”

He said the president should stand aside “as soon as possible”, though he qualified it by saying he would support him “unreservedly” if he insisted on remaining as the nominee.

But his statement’s effect was driven home in a later interview with CNN’s Jake Tapper, one of the two moderators in the 27 June debate with Donald Trump in which Biden’s hoarse-voiced and frequently confused performance and demeanour plunged his re-election campaign into existential crisis.

“Personally, I think Kamala Harris [the vice-president] would be a much better, stronger candidate,” Smith told Tapper, adding that Biden was “not the best person to carry the Democratic message”.

He implicitly criticised Democratic colleagues – and Biden campaign staff – who were calling for the party to put the debate behind them as “one bad night”.

“A lot of Democrats are saying: ‘Well let’s move on, let’s stop talking about it’,” said Smith. “We are not the ones who are bringing it up. The country is bringing it up. And the campaign strategy of ‘be quiet and fall in line and let’s ignore it’ simply isn’t working.”

Smith joins the ranks of five Democratic members of Congress who publicly demanded Biden’s withdrawal last week. He was among at least four others who spoke in favour of it privately in a virtual meeting on Sunday with Hakeem Jeffries, the party’s leader in the House.

Having the ranking member of the armed services committee join the siren voices urging his withdrawal may be particularly damaging to Biden’s cause in a week when he is to host a summit of Nato leaders in Washington.

The alliance’s heads of government and state will gather in the US capital on Tuesday for an event that is likely to increase the international spotlight on Biden, who is due to give a rare press conference on its final day on Thursday, an occasion likely to be scrutinised for further misstatements and evidence of declining cognitive faculties. Unscripted appearances have been rare in Biden’s three-and-a-half-year tenure.

In an interview with ABC’s George Stephanopoulos last Friday, Biden stressed his role in expanding Nato’s membership and leading its military aid programme to help Ukraine fend off Russia’s invasion as a key element of his qualification to continue as his party’s nominee and be re-elected as president.

In the surprise interview with Morning Joe on Monday, Biden put the blame for his current predicament on Democratic elites, an undefined designation which he may now expand to include Smith.