KASIE HUNT and SHANNON McCAFFREY, Associated Press

BEDFORD, N.H. (AP) — Mitt Romney says if Newt Gingrich can't take the heat generated by attack ads during the GOP presidential primary, he'll wilt during a one-on-one contest against President Barack Obama.

Appearing Wednesday on Fox News, Romney continued a nasty dispute between the two candidates over hard-hitting television spots as both vie for voters in Iowa and New Hampshire.

Gingrich, a former House speaker known for his rough-and-tumble campaign style, has claimed a political action committee working on behalf of Romney is running misleading and false ads against him.

Romney said he can't control what the independent PAC does due to federal rules that bar coordination with them. But he needled Gingrich, saying the former House speaker is too thin-skinned to go up against what he called Obama's "Hell's Kitchen."

Copyright 2011 The Associated Press.