(CNN) - Which one's the pot and which one's the kettle is open to debate-but Newt Gingrich and Mitt Romney are heading to their own version of a bake-off, one way or the other.
A kitchen analogy dominated heated rhetoric between the two Wednesday, which potentially came to a boil when Gingrich challenged Romney to go toe-to-toe next to the stove.
"If he wants to test the heat I will meet him anywhere in Iowa next week, one-on-one, 90 minutes, no moderator, just a timekeeper," Gingrich said at an event in Manchester, New Hampshire.
Earlier in the day Romney defended negative TV advertising, following Gingrich's calls for the former Massachusetts governor to denounce attacks ads funded by a super PAC that supports his candidacy
"If you can't stand the relatively modest heat in the kitchen right now, wait until Obama's Hell's Kitchen shows up," Romney said at a campaign stop in Keene, New Hampshire. "Obama's putting together a billion dollars. He's going to be attacking us day and night."
In response, Gingrich said he will happily go into the kitchen with Romney.
"Ask Gov. Romney, would he like to come and play in the kitchen? I don't think so," Gingrich said. "I don't think he wants to do anything except hide over here and pretend it isn't his fault that he is flooding the people of Iowa with falsehoods."
The former House speaker has steadily criticized Romney over negative advertising, a blitz of which were released on Gingrich ahead of the Jan. 3 Iowa caucuses. Romney has pointed to campaign finance rules that prohibit his involvement in activities of super PACs while refusing to renounce negative advertising, as Gingrich has recently done.
As for Gingrich's debate challenge, a watched pot never boils.