DES MOINES -- Looking for any advantage possible in the closing days before Iowans caucus, Mike Huckabee and Mitt Romney are making their final pitches in very different ways. The two Iowa front-runners' final pitches are telling of the way their campaigns see themselves: Romney's last advertisement is a positive spot; Huckabee is said to be planning a shot at Romney.

Romney today launched a closing advertisement lightly touching on the points he has been hammering home this year: Businessman who turned around the Olympics and several big companies, and who can now turn Washington around. Huckabee, battered by weeks of critical ads from Romney, plans a response, a senior adviser told the Wall Street Journal.

That response ad was cut Sunday, when Huckabee took a day off campaigning to attend church and a film session. The ad, to come out today, accuses Romney of distorting Huckabee's record to hide from his own.

As has been the pattern throughout the year, candidates only attack one another when they are behind or when their lead is threatened. It took Huckabee gaining a lead for Romney to start paying attention; now, with Huckabee's apex seemingly behind him, the former Arkansas governor is getting into the act.

The move carries significant risk: Iowa voters say they do not like negative advertising, and though such advertising remains an effective campaign tool, using it at the end of a crowded caucus campaign means the last thing voters will see is Huckabee going after Romney instead of showing off his own sunny personality, which boosted his prospects in the first place.

Iowa voters who stay up late, though, will have the opportunity to see the funny side of Huckabee the night before the caucuses. While writers are still staying away and most A-list celebrities have not committed to booking the show, Huckabee will join Jay Leno on the comedian's first night back from the writers' strike, which began November 5, the Hollywood Reporter writes.

Hanging out with Leno, even if only by satellite, could prove a big boost for the naturally humorous Huckabee. In the waning days of an increasingly nasty campaign, leaving caucus-goers with a pleasant memory of the candidate is crucial. Romney's is already on the air. Whether voters remember Huckabee in the same way could determine Iowa's outcome.