Mitt Romney set out Monday to defend a narrow lead against at least two insurgent candidates going into the Iowa caucuses, a contest that could either restore Romney's status as the race's frontrunner or once again shake up the field.

Romney is doing well in Iowa despite having all but ignored the contest earlier in the season. But while the former Massachusetts governor leads in recent polls, his 1- or 2-point advantage falls well within the margin of error. And with so many caucus-goers either undecided or open to changing their minds, GOP officials say the contest is anybody's game.

Ron Paul and Rick Santorum are nipping at Romney's heels, and both aim for a strong -- if not winning -- performance in Tuesday's caucuses. The volatile nature of the race lends hope to the rest of the candidates, who are banking on a strong organizational effort over the next 36 hours to out-perform the polls.

"Polls are polls," Rick Perry said Monday on Fox News, dismissing surveys that show the Texas governor struggling to break back into the top tier in Iowa...