Brown’s decision has been closely guarded for days, but it was confirmed by two people familiar with the event, where Brown will appear onstage with the candidate.

When reached early Tuesday afternoon, the Trump campaign’s spokesperson would not discuss the rally or possible guests. Brown was unavailable for comment.

Brown’s move could give Trump a significant boost, one day after the mogul lost the Iowa caucuses to Sen. Ted Cruz of Texas. Although Brown was defeated in his senatorial bid here, he has been popular GOP figure in New England ever since his stunning, come-from-behind victory in Massachusetts’s special election to fill the Senate seat in 2010.