Michael Minogue, a major donor to federal conservatives, announced a campaign for Massachusetts governor Wednesday morning after months of speculation over whether the South Hamilton resident would jump into the increasingly crowded Republican primary next year.

Minogue joins Mike Kennealy, a former cabinet secretary under Gov. Charlie Baker, and Brian Shortsleeve, a venture capitalist, in competing for the Republican nomination to challenge Gov. Maura Healey, a Democrat, as she seeks a second term in office.

In a video announcing his bid, Minogue criticized a “one-party system” in Massachusetts.

“This state has given us so much … but too many families don’t feel that promise anymore. They’re being squeezed by higher costs, ignored by politicians who care more about themselves than the

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