FARGO, N.D. — North Dakota is not accustomed to being one of the way stations on the path to the White House. Given its meager number of delegates and its tiny, remote media markets, it is rare for a presidential campaign to give this state the time of day.

But here was Senator Ted Cruz on Saturday, addressing the state’s Republican convention and leading the crowd of several thousand to a standing ovation with a thunderous appeal to North Dakota’s sudden relevance. “It is entirely possible the men and women gathered here will decide this entire primary, will decide this nomination,” he said.

Mr. Cruz also dispatched Carly Fiorina, a former rival who has endorsed him, to warm up the crowd before he spoke. Ben Carson worked the convention floor on behalf of Donald J. Trump, shaking hands and posing for pictures. Gov. John Kasich of Ohio sent Gordon Humphrey, the former two-term Republican senator from New Hampshire, to do his bidding.