HANOVER, N.H. — Republican presidential frontrunner Mitt Romney emerged unscathed yet again from a GOP presidential debate Tuesday in which contenders focused their attacks on the federal government they said is the source of the nation’s economic problems.

Buoyed by a major endorsement from New Jersey Gov. Chris Christie earlier in the day, Romney largely avoided confrontations and watched from the sidelines during the few dustups that punctuated a toned-down debate at Dartmouth College.