Republicans in Maryland have been ruled by Democrats for almost two centuries. They have been divided into gerrymandered districts that dilute their ability to elect members to Congress. And their disorganized ranks have left the party’s most extreme members with an outsize voice in state politics.

But on Tuesday, the often overlooked and bulging moderate middle of the Maryland GOP will be relevant — at least for a day. In the state’s first competitive presidential primary in a generation, polls and interviews suggest an overwhelming number of Republicans will vote for Mitt Romney.