John Bolton, former national security adviser to Donald Trump, has described the former US president’s act as “old and tired” and said the Republican party is ready to move on to a “fresh face”.

Bolton is the latest ex-White House official to condemn Trump after Republicans underperformed in this month’s midterm elections, which added to a losing streak that convinced some he is now hurting rather than helping the party.

“There are a lot of reasons to be against Trump being the nominee but the one I’m hearing now as I call around the country, talking to my supporters and others about what happened on 8 November, is the number of people who have just switched Trump off in their brain,” Bolton told the Guardian.

“Even if they loved his style, loved his approach, loved his policies, loved everything about him, they don’t want to lose and the fear is, given the results on 8 November, that if he got the nomination, not only would he lose the general election, but he would take an awful lot of Republican candidates down with him.”

Now 74, Bolton served as US ambassador to the UN under President George W Bush in 2005-06 and was a staunch advocate of the Iraq war. He became Trump’s national security adviser in 2018 only to be fired the following year, then wrote a scathing memoir that declared the president incompetent and unfit for office.

He now joins Trump’s vice-president Mike Pence, secretary of state Mike Pompeo, attorney general William Barr, UN ambassador Nikki Haley, chief of staff Mick Mulvaney and onetime ally Chris Christie in a growing rebellion among alumni making the case – overtly or subtly – that Trump has become an electoral liability.

They point out that Republicans lost the House of Representatives in 2018, the presidency and Senate in 2020 and the Senate again in 2022, while gaining a smaller-than-expected majority in the House. Paul Ryan, the most recent Republican speaker of the House, blamed the Trump factor, telling ABC News’s This Week with George Stephanopoulos: “I think it’s palpable right now. We get past Trump, we start winning elections. We stick with Trump, we keep losing elections.”

Last week Trump announced his third consecutive run for the White House only for his headaches to be compounded when the attorney general, Merrick Garland, named a special counsel to lead the federal investigations into his attempts to overturn his 2020 election defeat and removal of classified documents from the White House.

Yet the 76-year-old former president still commands a chunk of fervent and significant support in the Republican base. His power and influence were evident in Republican primary elections where many of his anointed candidates prevailed over establishment figures such as Congresswoman Liz Cheney of Wyoming.

Bolton acknowledged: “There’s no doubt Trump’s endorsement in the primary can be very valuable to a candidate in the Republican party. But relying on that endorsement or trumpeting yourself as the Trump-endorsed candidate is poisonous in the general election. So if you actually want to win elections, Trump is not the answer.

“William F Buckley [the conservative author] once had a rule that in Republican primaries he supported the most conservative candidate capable of winning the general election and, under that theory, Trump loses.”

Bolton said he has conducted his own polling that shows Trump’s base within the party has been declining slowly but steadily for two years.

He said: “One question we asked was: do you want Trump or do you want a fresh face? I think in our last poll over 50% said they wanted a fresh face. That’s only going to continue. I personally don’t think Biden is going to end up running on the Democratic side and that’ll have an impact as well.”

Pence, Pompeo and Christie are among potential challengers to Trump for the 2024 nomination but the early frontrunner is Ron DeSantis, who delivered a “red wave” to Florida when he was easily re-elected as governor. DeSantis is a former navy lawyer who served at the base in Guantánamo Bay and in Iraq.

His foreign policy positions are likely to sit well with Bolton and other foreign policy hawks. DeSantis has condemned Biden’s chaotic withdrawal from Afghanistan, expressed opposition to the Iran nuclear deal and taken a hard line on China, Cuba and Venezuela. In 2019 he reminded his followers that he had “promised to be the most pro-Israel governor in America”.

Bolton said he first met DeSantis before the latter first ran for Congress in 2012. He noted that DeSantis’s roommate in Iraq was Adam Laxalt, who worked for Bolton in the Bush state department and narrowly lost an election for the Senate in Nevada earlier this month.

DeSantis has “had a very successful run as governor of Florida”, he said. “He won re-election on 8 November with a big majority. A lot of people look to him as the next generation candidate. That’s one of Trump’s biggest problems – his act is old and tired now.”

But Bolton, who has his own Pac and Super Pac to raise funds for Republicans, insisted he was not yet throwing his weight behind any 2024 contenders. “I would certainly be available and happy to talk to any of the candidates that wanted to talk about foreign policy and happy to help me make them all be better prepared to be the nominee.”

The next primary could also expose and exacerbate a foreign policy split in the Republican party between an interventionist wing, personified by Bolton and Liz Cheney, and “America first” isolationism embodied by Trump and Congresswoman Marjorie Taylor Greene, who has called for a halt to funding Ukraine’s fight against Russia.

Bolton, founder of the Foundation for American Security and Freedom, commented: “Within the party as a whole, support for the Ukrainian government and people are overwhelming. I do plan to spend some time in the next two years working against what I would call the virus of isolationism within the Republican party to make sure it does not become a serious force.”