Romney and Christie will hold an event Tuesday in New Hampshire ahead of the presidential debate set at Dartmouth, N.H., where Christie will announce his support, the campaign said.
Christie had been considering a presidential run in 2012. He decided last week not to mount a campaign.
Christie’s financial supporters had been waiting for him to decide before backing a different candidate. The New Jersey governor’s endorsement will send much of that cash to Romney. Romney also stands to benefit from the budget-cutting Christie’s ties to the tea party, a group of voters that Romney has struggled to win over.