The businessman will take all 16 of the state's delegates.
Rhode Island offers 19 delegates on a proportional basis.
It’s still unclear how many of Connecticut’s 28 delegates he will take.
The businessman will win a majority of Maryland’s 38 delegates.
The Keystone State's 71 delegates make it the biggest prize of the Tuesday slate.
Ted Cruz has bested Trump in winning delegates at past state conventions.
“I have never been more worried about the Republican Party breaking apart than I am today.”
The governor said the Cruz camp backed out of a deal for a "unity slate" of delegates.
"Every single debate, I beat Ted Cruz. He was supposed to be a good debater."
He linked Obama's foreign policy to Trump, pledging to "stand unapologetically" with Israel.