The win puts Trump just a few dozen delegates from the 1,237 threshold.
"We're going to get them because he's not going to win," Trump added.
“Even Bill Clinton chose other women, so you should too!” a Trump surrogate told the crowd.
Former "Little House on the Prairie" actress Melissa Gilbert is ending her congressional bid in Michigan.
"It was a very unusual political year," he said.
The former GOP rival cited the vacant Supreme Court seat as the reason for his endorsement.