Donald Trump should quit the race for the Republican nomination in 2024 if he is indicted in New York over a hush money payment to a porn star during his victorious run in 2016, a prospective rival said.

“It doesn’t mean that he’s guilty of it or he should be charged,” said Asa Hutchinson, a former governor of Arkansas. “But it’s just such a distraction that would be unnecessary for somebody who’s seeking the highest office in the land.”

Hutchinson has not declared a run. Nikki Haley, a former South Carolina governor, remains Trump’s only declared opponent from the Republican mainstream. The governor of Florida, Ron DeSantis, is Trump’s only serious challenger in polling.

Like other relative moderates, Hutchinson is a vanishingly small presence in polls regarding the nascent field.

He told USA Today: “When you’re looking at Trump, it’s going to be a circus.”

Widespread reporting has said an indictment is expected soon in the hush money case, which involves the payment of $130,000 to Stormy Daniels, an adult film maker and actor who says she had an affair with Trump in 2006.

Trump denies the claim, often abusing Daniels in misogynistic terms. But the man Trump directed to pay Daniels, his former lawyer and fixer Michael Cohen, is due to testify before a grand jury on Monday.

Trump has also been invited to testify, a sign an indictment is near. The Manhattan district attorney, Alvin Bragg, is reported to be preparing to criminally charge Trump for false accounting business records with an intent to defraud, in relation to New York election law.

Mark Pomerantz, a prosecutor who quit Bragg’s team, recently called the Daniels payment a “zombie case” that would not die.

But David Shapiro, a former FBI agent who now lectures at John Jay College of Criminal Justice, told the Associated Press it could be “especially difficult” for Bragg to prove intent and knowledge of wrongdoing.

Trump, Shapiro said, is “loud, he’s brash, so proving that he had specific intent to fraud, one is almost left with the idea that, ‘Well, if he has that specific intent of fraud, he has it all of the time, because that’s his personality.’”

Trump claims Bragg is politically motivated, as a Democrat, and racist because he is Black.

At CPAC earlier this month, the former president told reporters he “won’t even think about leaving” the race, as an indictment would “probably … enhance my numbers”.

Optimistically, Hutchinson told USA Today the man who left office twice impeached, the second time for inciting a deadly attack on Congress in an attempt to stay in power, should withdraw “out of respect for the institution of the presidency of the United States.

“And that’s a distraction [and it] is difficult to run for the highest office in the land under those circumstances.

“I know he’s going to say [the charges are] politically motivated and all of those things, but the fact is, there’s just a lot of turmoil out there with the number of investigations going on.”

Trump also faces federal investigation of his election subversion attempts, incitement of the January 6 attack and retention of classified records. A state investigation of his election subversion in Georgia is well advanced.

In New York, his business faces a civil fraud suit and his chief financial officer was sentenced on tax charges in January. Trump also faces trial in a defamation suit from a writer who says he raped her.

Trump denies all wrongdoing, claiming witch hunts by his political enemies.

On Sunday, on NBC’s Meet the Press, Kevin Cramer, a Republican senator from North Dakota, was asked if Trump should step aside if he is indicted in “Manhattan or Atlanta or Washington”.

“Donald Trump’s not going to take advice from the party or from me,” Cramer said.

“But I think what will happen is, if he’s indicted, that becomes one of the factors in whether he wins primaries or not. The other factor is who else is in the race and who can make the best case.”

DeSantis, Cramer said, “has certainly earned the right to be at the head of the class, not just through his political rhetoric but through his successful governing of a very large state.

“We’ve seen him out on the stump a little more now doing the things that potential presidential candidates do. I think it will help that debate along. The challenge becomes if there are too many people in the race.”

Polling has shown how a split field could hand Trump the nomination without a majority, as happened in 2016.

Cramer said: “Mike Pence, Mike Pompeo, certainly my friend Tim Scott would all be good candidates who understand the Trump doctrine but have a demeanor that’s probably more suitable to the swing voter.

“And at the end of the day, what’s most important for primary voters to think about is not just who they love the most but who can win for the country and who can win for the party. Because we’re in desperate need of some new leadership.”