The November election for governor of Connecticut will be a rematch of 2010’s razor-close contest.

Thomas C. Foley, a Greenwich businessman and a former ambassador to Ireland, handily defeated the State Senate minority leader, John P. McKinney, on Tuesday to win the Republican nomination, according to unofficial results.

Mr. Foley, who captured about 56 percent of the vote to Mr. McKinney’s 44 percent, will take on Dannel P. Malloy, the incumbent Democratic governor, who beat him by about 6,500 votes four years ago.

“Change is on the way; change is coming to Connecticut,” Mr. Foley said, addressing supporters in Waterbury late Tuesday. “Dan Malloy has had his chance, and change is coming.”

“I’m a businessperson,” Mr. Foley said, after ticking off some problems in the state such as high taxes, poorly maintained bridges and underperforming schools. “I know how to fix these problems. I’ve been doing them for 35 years and will represent everyday citizens, not insiders, not special interests.”