"The people are behind Donald Trump. You're going to see a rally behind him when he wins the convention in July in Cleveland," Emineth told CNBC's "Squawk Box" on Tuesday, as Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island held primaries.
Pennsylvania represents the biggest prize with 71 delegates up for grabs.
Despite expectations to the contrary, Emineth said he does not see a contested convention beyond one ballot, expressing confidence that Trump will amass the 1,237 delegates needed to clinch the nomination.
Ahead of Tuesday's contests, Trump has 845 delegates, Texas Sen. Ted Cruz has 559, and Ohio Gov. John Kasich has 147, according to NBC News.
Emineth, formerly head of the North Dakota Republican National Committee, estimates about 300 to 450 unbound delegates are going into the convention because of the different rules in various states.
"[Even] if Donald Trump is 50 to 100 [delegates] short going into it, he will get his fair share of [the unbounds] and that's why he'll win on the first ballot," Emineth said. "People want to elect a winner."
Trump hasn't even started focusing on Clinton yet, Emineth said.