DES MOINES — The line outside the Trump rally on Thursday night was perhaps not the safest space to try to conduct a Socratic dialogue about the nature of truth. But Joe Walsh — former Tea Party congressman, former right-wing radio host, current Trump opponent — leaned right in.
“I’m a Republican and a conservative and I’m challenging Trump in the primary,” he announced to a Trump supporter festooned in campaign-themed clothing. “Let me ask you this: Has Donald Trump ever lied to the American people?”
A nanosecond passed, while the supporter bristled at this unfamiliar scenario. “Nothing comes to mind,” he said.
Mr. Walsh mentioned that President Trump, despite promising fiscal responsibility, had presided over an increase in the federal deficit greater than that under President Barack Obama.
“I couldn’t speak to that,” said the supporter, who did not want to give his name, on account of not trusting reporters. “Sometimes we say things and they might not be full of truth, but we all make mistakes. He’s a straight guy. I love his tenacity.”
Another supporter had been growing noticeably agitated as he heard this exchange. (He also did not want to give his name.) “Let me ask you something!” he said. “Has Adam Schiff ever lied?” he asked, referring to Representative Adam B. Schiff, a lead impeachment manager. “What about ‘Shifty Schiff’? You’re like Adam Schiff” — he pointed at Mr. Walsh — “lying to the American people!”
If it is hard to be a Democratic candidate in the crowded and uncertain 2020 field, it may be even harder to be a Republican trying to present a legitimate alternative to a president whose supporters won’t entertain the idea of anyone else, and who is all but certain to be the party’s nominee.
Mr. Trump won Iowa with 51 percent of the vote in 2016 and still has high approval ratings from the state’s Republicans. But if local party members were feeling rather left out this past week with so much focus on the Democrats — all those candidates, all those events — the president had swooped in to remind them that there was a new election coming up and that, as he said on Twitter, he was “America’s Greatest President.” And Mr. Walsh was there to present a countermessage: No, he wasn’t.
There used to be three Republican challengers — Mr. Walsh, former Gov. William F. Weld of Massachusetts and former Gov. Mark Sanford of South Carolina — but Mr. Sanford dropped out just two months after entering the race, and now there are two.
The odds are never great for same-party challengers when an incumbent president runs for re-election. But the candidates say that as Mr. Trump has consolidated his hold over the Republican Party, things have gotten increasingly difficult. For one thing, the party has, in 37 states and territories, changed the rules for choosing delegates to the Republican National Convention, a move likely to limit dissenting voices on the convention floor.
Also, many state Republican committees have canceled this year’s primaries altogether; others have put up prohibitively difficult barriers for challengers to enter or said they would hold primaries with just a single name — Donald J. Trump — on the ballot.
“They’re behind Trump lock and key,” Mr. Walsh said. When he showed up at the Republican National Committee in Washington last month to lodge a complaint about what he said was “the disenfranchisement of millions of Republican voters,” the guards wouldn’t let him past the lobby.
Mr. Weld gamely made his own voice-in-the-wilderness case to several dozen people at Cornell College in Mount Vernon, Iowa, on Saturday. He was joined by Jim Leach, a longtime member of Congress from Iowa and former chairman of the National Endowment for the Humanities, whose public endorsement of Mr. Weld seems like a daring move in the current climate. (“The only reason I can is that I am not an elected official,” Mr. Leach said by telephone.)
In a phone interview, Mr. Weld said he felt like “a two-headed cow at the Iowa State Fair,” a figure of curiosity on account of his uphill campaign. He said that many Republicans shared his view of the president but were afraid to say so.
“The party may be redeemable, but the president is not redeemable,” he said. “He’s gone too far in the direction of wanting to undermine democratic institutions to amass power for himself. ”
He and Mr. Walsh have also been making their case to voters in one-on-one conversations in bars and coffee shops in Des Moines in the lead-up to Monday’s caucuses. James Marren, who showed up at the Exile bar to talk to Mr. Walsh the other night, said that he had encountered the candidate before, at a veterans’ group in Dubuque, and that he was a changed man from his days as a right-wing, pro-Trump radio host spouting incendiary conspiracy theories.
“It was all Democrats and him,” said Mr. Marren, 75, a Democrat so impressed by Mr. Walsh that he is talking him up to his Republican friends. “He said that Trump’s a liar and a traitor. He apologized for what he used to say on his radio show. He was amazing.”
But at the Trump rally, it was a different story. Virtually everyone Mr. Walsh spoke to disagreed with virtually everything he said.
When he mentioned Ukraine, a Trump supporter said that “Obama got that started.” When Mr. Walsh pointed out that Mr. Trump had vowed to make Mexico pay for the border wall, but was instead using money from the United States military budget, another supporter first said that Mexico was indeed paying for it, in that there are fewer Mexicans crossing the border and thus fewer Mexicans sending “American money” back home. Then she said: “Well, he would have made the Mexican government pay for it, but a lot of people are standing in his way.”
After just a few minutes of these encounters, Mr. Walsh was beginning to seem like the most masochistic person in Iowa.
“These are the people who listened to me on the radio” when he was a darling of the right, he said. “I can relate to why they voted for Trump. I voted for him in 2016. But then I saw that he lies damn near every time he opens his mouth.”
The turning point for him was Mr. Trump’s 2018 meeting in Helsinki with Vladimir V. Putin, the Russian president, in which Mr. Trump said he believed Mr. Putin’s claim — contrary to American intelligence — that Russia had not interfered in the 2016 election. “That was the most unpatriotic thing I’ve ever seen an American president do,” Mr. Walsh said.
Suddenly, in line, Mr. Walsh ran into an old neighbor from Chicago, Mark Weyermuller, who had supported him in his congressional days but had traveled to Des Moines on this occasion for the president.
It was an awkward encounter. “You know they’ve canceled the Republican primaries in 10 states,” Mr. Walsh said.
Mr. Weyermuller said that he had not heard that before but that it was “sort of a goofy system.”
“I’m happy for you, but I’m supporting Donald J. Trump,” he said, and he moved on.
Then there was Matt Locke, a.k.a. the Conservative Sharpshooter, a talk-radio and podcast host who had traveled from Texas to spend an evening listening to Mr. Trump.
“You’re a Tea Party guy, Joe,” Mr. Locke said. “What happened?”
The two talked at loud cross-purposes about topics like corruption among Ukrainian prosecutors; Democrats who have foreign investments; and, once again, whether Mr. Trump has ever lied. (“I don’t know,” Mr. Locke said sarcastically. “Has he?”) The discussion turned to the time Mr. Trump publicly invited China to investigate former Vice President Joseph R. Biden Jr. and his family.
“He wasn’t serious!” Mr. Locke said. “He was joking. You gotta have a sense of humor.”
The two agreed to vehemently disagree, and Mr. Walsh went off into the cold to find some other voters who also disagreed with him.
“I don’t mind Joe,” said Mr. Locke, “but he doesn’t have a snowball’s chance in hell.”