He has tried workshopping versions of those critiques as Twitter attacks, referring to Mr. Biden as “sleepy” and “swampman,” and blaming him for the 1994 crime bill that critics say increased mass incarceration. West Wing aides have been discussing another criminal justice reform event as a vehicle to underscore Mr. Biden’s support of the crime bill.
During a state visit in Tokyo, Mr. Trump appeared to side with Kim Jong-un, the North Korean leader, by saying on Twitter that he, too, called Mr. Biden a “low IQ individual, & worse.”
In Iowa, Mr. Trump will finally be in a place where he will be expected to go after Mr. Biden, rather than be criticized for it. He will also attend a fund-raising dinner for the state Republican Party chairman, Jeffrey Kaufmann, an event his campaign aides said they had wanted to get on the books for months, as a way to incentivize other state party leaders to work hard on behalf of Mr. Trump.
“He didn’t win Iowa in our caucuses, but he still maintained Iowa as a special state for him,” Mr. Kaufmann said. “I’ve visited with him in the Oval Office, and every single time he not only shows his support for our state, but he shows he understands the issues out here.”
This event — along with a winter and spring of MAGA rallies, mostly in reliable states — will be a rehearsal for next week. Mr. Trump, hoping to turn the attention of the race back onto himself, will officially kick off his re-election campaign on June 18 with a megarally in Florida, a state he must win in 2020 but where his numbers are softer than the campaign would like.
But just a week before the rally, Mr. Trump continues to function without a chief political strategist, people involved in his campaigns said. The president’s lead pollster, Mr. Fabrizio, is someone Mr. Trump resisted hiring in 2016, and his blunt approach is not always welcome by a candidate who prefers good news and can take a shoot-the-messenger approach to receiving information he does not like.
Longtime aides and advisers said they expected him to hit his stride once he had a clear opponent in front of him like he will have, for one day, in Iowa.
“President Trump is always strongest when he has a direct foil,” Mr. Miller said. “I can’t imagine him not taking advantage of the opportunity to jab at Biden.”