(AP) - Mitt Romney is moving on from Tuesday's narrow victory in Iowa to next week's primary in New Hampshire, and anticipating sharper criticism from his rivals.

The former Massachusetts governor was declared the winner of the leadoff Republican presidential caucuses early Wednesday by a mere eight votes over Rick Santorum.

Santorum, a former Pennsylvania senator, declared "Game on" after emerging as Romney's foremost conservative rival for the primaries yet ahead.

Texas Rep. Ron Paul ran third and former House Speaker Newt Gingrich was fourth, and both men vowed to carry the fight to New Hampshire and beyond.

Texas Gov. Rick Perry came in fifth and told supporters he would return home to Texas to reassess his candidacy. Minnesota Rep. Michele Bachmann was a distant sixth, and her campaign appeared in disarray.