WASHINGTON (AP) — Mitt Romney keeps putting his foot in his mouth, and his rivals are happy to watch him do it.The Republican presidential contender has told voters he's OK with the housing market hitting rock bottom. He's told voters in Iowa that "corporations are people, my friend." He's told a Florida group that he, too, was unemployed. In Arizona, he told a car dealer that he only buys domestic cars — "a couple of Cadillacs."Romney has tripped himself up with such off-the-cuff comments that only reinforce the perception of him as an out-of-touch elitist. So far, his impolitic comments haven't proved disqualifying.But if Romney wins the nomination, those moments will come back to haunt him. The Democratic National Committee is already laying the groundwork and running ads.