G.O.P. Rivals Don’t Attack Trump in Iowa. But He Doesn’t Return the Favor.

Candidate after candidate at an Iowa Republican dinner on Friday avoided so much as mentioning the dominant front-runner in the race, former President Donald J. Trump.

But when Mr. Trump took the stage after more than two hours of speeches by his lower-polling rivals, it took him less than three minutes to unleash his first direct attack of the night on his leading challenger, Gov. Ron DeSantis of Florida.

Mr. Trump not only suggested that Mr….