Former President Donald J. Trump kicked off a flurry of campaign activity on Wednesday with an eye toward a decisive victory in Iowa that would crush his Republican rivals’ hopes of emerging with any kind of momentum in the presidential primary.

He’ll have a little help from his friends.

Mr. Trump gave a speech in Coralville, a small city in eastern Iowa, on Wednesday, before planned stops in New Hampshire, the second nominating state, and Nevada, third on the primary calendar, over the weekend. Mr. Trump will return to Iowa on Tuesday for a speech in Waterloo, a city in the northeastern part of the state.

But as Mr. Trump is shoring up support in the other early states, prominent surrogates will hit the ground in Iowa on his behalf in a display of the particular advantages he enjoys as the former president and the primary’s dominant front-runner. In the coming week, his campaign will hold events in Iowa with Representative Matt Gaetz of Florida, a conservative firebrand and one of Mr. Trump’s closest allies in Congress, and Ben Carson, the former president’s secretary of housing and urban development.

Mr. Trump enters this campaign stretch buoyed by recent polling that shows him holding his edge in the primary and in a strong position against President Biden in next year’s general election should the pair meet for a rematch. Mr. Trump’s allies in the Republican-led House of Representatives have approved a formal impeachment inquiry of Mr. Biden that could have ramifications for the president’s campaign even as their investigations thus far have failed to produce evidence of high crimes or misdemeanors.

And as early nominating contests near, there has been little progress from rivals hoping to claim the mantle of Mr. Trump’s chief primary challenger. The Republican governors of Iowa and New Hampshire have each endorsed different candidates, highlighting the challenge that faces the candidates as they each try to coalesce the anti-Trump faction behind them.

A recent Iowa poll even found that Mr. Trump’s support in the state went up as candidates left the race. His popularity has not waned even as other candidates have barnstormed the state to speak to voters and urge them to consider alternatives. And though he faces four upcoming criminal trials, one of which is scheduled to start in March, surveys suggest that the charges have not affected his standing in the Republican primary.

Since September, Mr. Trump has held a number of “commit to caucus” events in Iowa that are meant to help his campaign convert his massive popularity in the state to a strong showing at the caucuses.

Mr. Trump’s event next week in Waterloo will be his sixth campaign stop in Iowa this month. Vivek Ramaswamy, an entrepreneur trailing Mr. Trump significantly in the polls, was scheduled to hold seven campaign events in the state on Wednesday alone. He also took part in a CNN town hall Wednesday evening.

Still, the Trump campaign has gradually ramped up its event schedule as the caucuses have approached and plans to continue to do so. Mr. Trump has promised to blitz the state in January, and more events with surrogates are expected.

Mr. Trump also has significant advantages in polls in New Hampshire, the first state that he won during his successful campaign for president in 2016. And the contest in Nevada is tilted in his favor.

Mr. Trump on Wednesday spent much of his speech on the economy, attacking Mr. Biden for not doing enough to address gas prices and inflation. He mocked his rivals and the Republican governors who have endorsed them.

The speech in Coralville was Mr. Trump’s first campaign event since an interview in which he declined outright to deny that he would abuse power to retaliate against his political opponents. When pressed, Mr. Trump vowed that he would not be a dictator, “other than Day 1.”

The former president did not address that comment, which he has since said was a joke, on Wednesday. But he defended it in a speech on Saturday in Manhattan.

During his keynote address at a gala for the New York Young Republican Club, Mr. Trump confirmed that he “wanted to be a dictator” for a day, only to build a border wall and drill for oil. He called the suggestion that he would be a threat to democracy Democrats’ “newest hoax.”