The starting gun has been fired and the race for the White House is under way. But in Iowa, where the first-in-the-nation Republican caucuses are just a year off, the landscape is icy and snowy and eerily silent.

There is no great mystery why: the Donald Trump effect.

“These folks must be watching Trump’s poll numbers and that’s why there’s a delay,” said Art Cullen, editor of Iowa’s Storm Lake Times. “Trump and [Florida governor Ron] DeSantis are doing this sparring around the ring. Others are watching to see if somebody takes a blow and gives them an opening.”

At the same stage in 2019, at least a dozen Democratic contenders for the presidency had either been to Iowa or announced plans to visit soon. “We were getting one every other week,” recalled Cullen, noting that the first major candidate forum took place in March.

But among potential Republican hopefuls for 2024 only the former Arkansas governor Asa Hutchinson has visited so far this year while Tim Scott, a senator for South Carolina, and Kari Lake, a former candidate for governor of Arizona, seen as a possible Trump running mate, have lined up appearances later this month.

Trump, the only declared candidate so far, has not yet been to Iowa but his campaign is finally moving up a gear. Last weekend the former US president addressed Republicans at small-scale events in two other early voting states, New Hampshire and South Carolina, vowing to “complete the unfinished business of making America great again”. He is issuing policy statements, building infrastructure and unveiling endorsements that signal: catch me if you can.

It is a surprisingly orthodox approach from the most unconventional of candidates. The 76-year-old was twice impeached, was blamed for thousands of deaths in the coronavirus pandemic and encouraged a violent coup on 6 January 2021. He is facing multiple criminal investigations and yet, with remarkable insouciance, styling himself as incumbent in all but name and betting on voters’ short memories.

He is also throwing down the gauntlet to would-be challengers, daring them to make the first move. While there are signs that some are preparing to take him on, none has yet launched a full-frontal attack on Trump or Trumpism, apparently wary of earning his wrath and alienating his base.

Bill Whalen, a former media consultant for California politicians including former governor Arnold Schwarzenegger, said: “I don’t think anybody wants to run and be a bad guy wrestler, be seen as the heel whose one purpose is just to attack Donald Trump. It’s not a ticket to success and it’s grinding because Trump will return fire. What’s the old saying about wrestling with the pig in the mud: you get dirty and the pig enjoys it more than you do.”

It emerged this week that Nikki Haley, 51, who was South Carolina’s governor before serving as Trump’s ambassador to the United Nations, is planning to announce her candidacy in Charleston on 15 February. In 2021 Haley told the Associated Press that she “would not run if President Trump ran”, but she has since changed her mind, telling Fox News that she could be part of “new generational change”.

In South Carolina last Saturday Trump told WIS-TV that Haley had called him several days earlier to seek his opinion. “She said she would never run against me because I was the greatest president, but people change their opinions, and they change what’s in their hearts,” he said. “So I said, if your heart wants to do it, you have to go do it.”

Trump appears more threatened by – and less courteous towards – DeSantis, who won re-election in a landslide in Florida and is beating him in some opinion polls. Trump, who helped elevate DeSantis in the past, has dubbed him “Ron DeSanctimonious” and said a DeSantis challenge for the 2024 nomination would be “a great act of disloyalty”.

But even DeSantis – who is not expected to declare until the Florida legislature adjourns in the spring – has pulled his punches so far. He responded to Trump’s attack with only a coded rebuke, drawing a contrast between his own success and Trump’s failure at the ballot box in 2020: “Not only did we win re-election, we won with the highest percentage of the vote that any Republican governor candidate has in the history of the state of Florida.”

Other possible candidates such as Trump’s former vice-president Mike Pence and his ex-secretary of state Mike Pompeo have been similarly circumspect in critiquing their former boss, taking the odd swipe while also praising his administration and their parts in it. Taking on Trump directly carries huge political risks, as rivals such as Jeb Bush, Ted Cruz and Marco Rubio discovered via name calling, insults and humiliation in 2016.

John Zogby, an author and pollster, said: “There is the the sense that alienating Donald Trump is a very thankless task. Trump comes down with a hammer, an anvil and a safe from the sky. Even though it is clear that a lot of the magic is gone from Trump, by the same token he can do extensive damage. He still has his own forum and he still has his own loyal following and he can suck up all the negative oxygen. Whether Trump wins or loses, he blocks.”

Even so, Trump could soon have company on the campaign trail, not least because primaries often draw long-shot candidates who would welcome the consolation prize of a book deal, radio show, TV pundit gig or slot as winner’s running mate.

State governors who might seek to build their brand nationally include Greg Abbott of Texas, Brian Kemp of Georgia, Kristi Noem of South Dakota, Kim Reynolds of Iowa, Chris Sununu of New Hampshire and Glenn Youngkin of Virginia.

It remains to be seen if forthright Trump critics such as Liz Cheney, a former congresswoman from Wyoming, and Larry Hogan, the ex-governor of Maryland, will throw their hats in the ring. Few observers expect such a candidate to win a primary more likely to offer voters different flavors of “Make America great again” (Maga), with culture warrior DeSantis aiming to prove himself a younger, more dynamic version of the brand than the Trump original.

Drexel Heard, a Democratic strategist, said: “It’s going to be very interesting to see how Maga Nikki Haley becomes in the primary. I find Nikki Haley to be intelligent but she is going to have to go full tilt Maga to get through this primary because she’s up against somebody like Ron DeSantis, who is already coming out of the gate with red meat.”

With a fiercely loyal base, Trump stands to benefit from a divided field, just as he did in 2016. In South Carolina he has already bagged the endorsements of Governor Henry McMaster and Senator Lindsey Graham, stealing a march on Haley and Scott within the state. But as Trump seeks to normalise himself with a traditional campaign so far, there are also important differences from seven years ago.

Whalen, the former California consultant who is now a research fellow at the Hoover Institution at Stanford University in Palo Alto, said: “First, there are legal issues. Now, some are more serious than others but if you’re running for president and you’re taking the fifth amendment 400 times, it’s not a good look for a candidate.

“Second, he has a record to deal with that he didn’t have. Donald Trump was a hypothetical in 2015 and 2016, a tabula rasa when it came to holding office. Now he has four years in office which he has to explain. He’s not a hypothetical, he’s somebody who has had the job before, so voters have to make the calculation: do they want him in office again?

“Third, there was not a Ron DeSantis-like figure in 2016. There was nobody quite in the same position as DeSantis in terms of the ability to do three things at once: monetise, point to a very successful record in his state and play the game that Trump plays. That is what makes DeSantis an option that wasn’t there for Republicans in 2016. In 2024, there is someone potentially who could fight fire with fire.”

Other commentators agree that, despite the slow start in Iowa, the Republican primary looks set to be far more competitive than anyone imagined a year ago. The party was willing to overlook any number of Trump’s lies and misdemeanors but not the miserable performance of his handpicked candidates in last November’s midterm elections. The self-proclaimed winner has become a serial loser: his fundraising numbers so far have been relatively disappointing.

Larry Jacobs, director of the Center for the Study of Politics and Governance at the University of Minnesota, said: “I’m not seeing a whole lot of Trump fear. It looks to me that there has been a truly wide agreement in Republican circles that Trump is weak and that he’s beatable. Moreover, he may be even weaker with the coming indictments. To me what’s going on right now is just confirmation that Trump’s hold on the Republican party is loosening.

“I would say it’s pretty open. Trump is a favourite but he’s got some very serious long-term viability issues in the field that is obviously no longer intimidated by him. Republicans are tired of losing.”