Twice given a chance to say he would support Donald Trump if he was the Republican nominee for president in 2024, Mike Pence, Trump’s former vice-president, declined to do so.

“I’m very confident we’ll have better choices come 2024,” Pence told CBS on Wednesday. “And I’m confident our standard-bearer will win the day in November of that year.”

Pence also said “different times call for different leadership”.

Trump, the former South Carolina governor Nikki Haley and Vivek Ramaswamy, a biotech entrepreneur and author, are the only declared candidates for the Republican nomination. The Florida governor, Ron DeSantis, is widely expected to run and is Trump’s only challenger in polling.

Pence joins Haley in scoring single digits in most surveys. He told CBS he would make a decision on whether to run “this spring”.

Pence’s reluctance to commit to supporting Trump points to a possible outcome feared by Republicans: that Trump will split the party either by winning the nomination without majority support or losing it and refusing to support the winner.

Trump has refused to commit to supporting another nominee.

Haley has refused to attack Trump personally but she has called for mental competency tests for politicians over the age of 75. Trump is 76.

Pence said: “I come from southern Indiana, where people think most politicians should have a competency test. No, I think the American people can sort that out. I really do.”

He added: “I really believe that the conservative movement has always been animated by ideas.

“We’ve had big personalities, from [Ronald] Reagan all the way to Donald Trump. But I think it’s the ideas – of commitment to a strong national defense, fiscal responsibility, limited government and traditional values – that really I think created this movement and still sustain it.”

Pence claimed “the record of the Trump-Pence administration” – four chaotic years which ended with Trump refusing to call off supporters who chanted for Pence to be hanged as they stormed Congress – bore out such Republican values.

He also said voters were telling him “they want to see us get back to the kind of civility in politics that the American people show each other every day”.

According to testimony before the House January 6 committee, Trump told aides Pence deserved to be hanged, for refusing to block certification of Joe Biden’s win.

The Department of Justice is still investigating Trump’s election subversion and incitement of the Capitol attack.

Pence has been celebrated for defying Trump but he is now challenging a subpoena from the special counsel, Jack Smith.

Pence told CBS: “The notion of compelling a former vice-president to appear in court to testify against the president with whom they served is unprecedented, but I also believe it’s unconstitutional.”