Chris Christie (Creative Commons)

Christie announced his endorsement at an event in Hanover, N.H., hours before the GOP Debate at nearby Dartmouth College. 

The event comes as Herman Cain continues to build momentum, threatening to take away front-runner status from Romney. Rick Perry continues to fall in the polls. 

It also comes on the heels of news that Romney's team advised "Obamacare."

Romney's universal-health-care program, no doubt, was a model for President Obama's federal law, but White House visitor logs now show that three Romney aides paid Obama's team at least a dozen visits. 

Conservatives have criticized Romney and his Massachusetts universal-health-care program, pointing out similarities to Obama's law.