It is an obvious line of attack that has been creeping into the arsenal of rivals trying to stop former President Donald J. Trump ahead of the Iowa caucuses on Monday — if nominated to be the Republican Party’s White House standard-bearer, the former president could very well be a convicted criminal by Election Day.
Gov. Ron DeSantis of Florida inched toward that cudgel at a debate on Wednesday night, warning that a “stacked left-wing D.C. jury” is likely to sit in judgment of Mr. Trump’s efforts to subvert the 2020 election, and asking, “What are the odds that he’s going to get through that?”
Then, he added, “what are we going to do as Republicans in terms of who we nominate for president? If Trump is the nominee, it’s going to be about Jan. 6, legal issues, criminal trials.”
Former Gov. Nikki Haley of South Carolina has been far more reluctant to broach his legal troubles, speaking almost daily of Mr. Trump as an agent of “chaos” and “disarray” without explicitly mentioning the 91 felony counts looming against him.
But perhaps taking their cues from voters leery of attacks on the former president, Mr. Trump’s closest rivals continue to avoid one ominous word: conviction.
For the Republican Party, the reality of Mr. Trump’s legal jeopardy is inescapable, and was underscored on Tuesday when he left the Iowa campaign trail to attend courthouse arguments on whether he can claim absolute legal immunity for any actions taken as president. Regardless of how voters feel about his indictments for subverting the 2020 election, mishandling highly classified documents and falsifying business records to cover up potential sex scandals during the 2016 presidential campaign, one of those cases could go to trial before the election.
And a conviction by a jury of his peers after a widely publicized trial could land differently than the indictments themselves, which were dismissed by Mr. Trump and most of his rivals as political efforts by Democrats to interfere with the presidential election.
“I actually still believe they will have a trial, and he will be convicted of at least one felony count,” said Asa Hutchinson, a former Arkansas governor and federal prosecutor still pursuing his quest for the Republican presidential nomination. “That puts the Republican Party in jeopardy: a flawed nominee, a historical precedent of a nominee convicted of a felony, and then a loss” in the general election.
That might sound like a potent argument for Mr. Trump’s more prominent foes, but many Republican voters don’t want to hear it. On Tuesday morning, at an Irish pub in Waukee, Iowa, Nick and Kadee Miller of Adel, Iowa, were awaiting Ms. Haley when both expressed doubts about the charges facing Mr. Trump. They supported the decisions of Ms. Haley and Mr. DeSantis to steer clear.
“I really do believe if you don’t have anything good to say, don’t say anything at all,” said Ms. Miller, a 49-year-old political independent who remains undecided about her choice of candidates.
Steph Herold, a 62-year-old retiree from West Des Moines, said such negativity spent on Mr. Trump would waste Ms. Haley’s time.
“What I love about Nikki is she speaks in facts and truth,” she said. During Mr. Trump’s presidency, “we all reverted back to the middle school playground, beating people up and being bullies. We don’t need more of that.”
Bruce Norquist, a 60-year-old cybersecurity analyst from Urbandale, Iowa, was certain a conviction would only bolster Mr. Trump’s support, as the indictments did last year.
But that is not what polling shows. Nearly a quarter of Mr. Trump’s own supporters told New York Times/Siena College pollsters in December that he should not be the Republican Party’s nominee if he is found guilty of a crime. Some 20 percent of those who identified themselves as Trump supporters said he should go to prison if convicted of plotting to overturn the 2020 election, and 23 percent of his supporters said in December that they believed he had committed “serious federal crimes,” up from 11 percent in July.
“When you put it that way, a convicted felon, no, I don’t want to vote for a convicted felon,” Ms. Miller said, breaking with her husband, who said he would “absolutely” vote for a convicted Mr. Trump “if he could beat Biden.”
On Wednesday, at a snow-covered vineyard in Indianola, Iowa, Laura Leszczynski, a 57-year-old security and information technology business owner from St. Mary’s, Iowa, was awaiting the entrepreneur-turned-presidential candidate Vivek Ramaswamy. Still undecided, she conceded she was not well-versed in the cases arrayed against Mr. Trump, but she was not willing to dismiss them.
“It just seems like there’s a lot there,” she said. “I’m not a lawyer. I haven’t studied up, but I am worried.”
Still, it is perhaps no coincidence that the two Republican candidates who were most ready to raise the prospect of conviction — Mr. Hutchinson and former Gov. Chris Christie of New Jersey — were seeing single digits or worse in national polling of Republican primary voters before Mr. Christie dropped out of the race on Wednesday.
In his farewell speech in New Hampshire, Mr. Christie returned to the moment in the August Republican primary debate when almost all the candidates on the stage raised their hand when asked if they would vote for Mr. Trump even if he were a convicted criminal.
“I want you to imagine for a second if Jefferson, Hamilton, Adams and Washington were frankly sitting here tonight,” he said. “Do you think they could imagine that the country they risked their lives to create would actually be having a conversation about whether a convicted criminal should be president of the United States?”
Yet that conversation continues.
In an interview on Friday with The Des Moines Register and NBC News, Ms. Haley danced around the prospects of a conviction for nearly three minutes: “He’s innocent until he’s proven guilty,” she said. “He’ll have to figure that out. I don’t have to deal with those court cases.”
Mr. DeSantis has been nudging toward acknowledging the danger. In an interview last month with the conservative radio personality Hugh Hewitt, he blamed Mr. Trump’s legal jeopardy on liberals out to get him: “I think it’s very difficult for a Republican, much less Donald Trump, to get a fair shake in front of a D.C. jury,” he said.
But as he has made his case against Mr. Trump more aggressively ahead of the Iowa caucuses, Mr. DeSantis has adjusted that argument.
“We’re taking a huge risk by empowering a jury of, probably an all-Democrat jury in the nation’s capital, the most Democrat area in the country, to pass a judgment,” he said in the NBC News interview, “because obviously if they rule against him, if they have a verdict against him, that’s going to hurt us in the election.”
Nicholas Nehamas contributed reporting.
