President Trump’s lead in the Republican primary is expanding to new heights even as fresh surveys are flashing warning signs suggesting a criminal conviction could turn some voters away.

Mr. Trump’s lead over Ambassador Nikki Haley has grown to 59 points after the Iowa caucuses, the largest bulge he’s posted yet in the primary competition, according to a new survey by Morning Consult.

The poll found that Mr. Trump enjoys 73 percent support, Ms. Haley is at 14 percent, and Governor DeSantis is at 12 percent.

Although Mr. Trump’s lead in the Republican primary is growing, other data suggest that the general election will be competitive and that a criminal conviction could pose a risk to Mr. Trump’s general election campaign prospects.

In a national survey from earlier in January, Reuter and Ipsos found that just 20 percent of the overall electorate would vote for Mr. Trump if he’s convicted of a felony. Broken down by party, 43 percent of Republicans, 3 percent of Democrats, and 14 percent of independents said they would vote for him if he’s convicted.

Another 28 percent of Republicans said they would not vote for him if he’s convicted of a felony, alongside 91 percent of Democrats and 55 percent of independents, accounting for 58 percent of all respondents.

A significant portion of respondents, 20 percent, said they didn’t know what they would do, including 28 percent of Republicans, 6 percent of Democrats, and 30 percent of independents. This suggests that support for Mr. Trump in the event of a felony conviction may be softer among the national electorate than entrance polling from the Iowa caucuses suggested.

That polling found that 63 percent of caucus goers would consider voting for Mr. Trump, even if he’s convicted of a crime. Mr. Trump currently faces charges in four separate cases. It is far from certain that there will be a verdict in any of Mr. Trump’s criminal cases before the election in November. 

Mr. Trump is facing multiple indictments — from three prosecutors — that would involve four criminal trials. His legal team has been maneuvering to move his trials until after the general election. Three of the cases appear to be headed for trials, or verdicts, that would come after the election. In the fourth trial, the federal case involving alleged election interference, Special Counsel Jack Smith has been moving for a May trial date, and the judge in the trial, Tanya Chutkan, has been sympathetic to that schedule. Mr. Trump’s campaign is seeking delays, and the matter is likely to be ultimately decided by the Supreme Court.

It is unclear if polling regarding a conviction can foretell the public’s response, especially as Mr. Trump ratchets up his rhetoric that the prosecutions are rigged, political “witch hunts.” He has made a point of attending his civil trials — for fraud and slander — in New York, even though his presence is not required, on the same day as he attends campaign rallies out of state.

As it stands, the 2024 general election is expected to be competitive regardless of a criminal conviction for Mr. Trump, with the Morning Consult poll showing Mr. Trump leading President Biden by only 2 points nationally.

A recent Wall Street Journal survey gives a sense of what might happen should Mr. Trump be convicted of a crime. The survey found that while Mr. Trump led Mr. Biden by four points when the poll was conducted in December, a conviction would swing that to a one point lead for Mr. Biden, 47 percent to 46 percent.

Mr. Trump has never won more than 47 percent of the popular vote. In 2016, Mr. Trump won with 46.1 percent of the popular vote, and in 2020 he lost with 46.9 percent of the popular vote.

While it matters where the voters who might abandon Mr. Trump in the event of a conviction are situated, if even a few percentage points of voters decide to vote for Mr. Biden or simply stay home, it could be enough to swing competitive states like Georgia, Pennsylvania, Wisconsin, Arizona, and Michigan.