What happened to Rudy Giuliani? I thought he was the frontrunner for the republican nomination.?

Rudy has been a very popular candidate for president amongst Republicans, mainly due to his experience after 9-11 and his established record of turning around New York City. But he's been hampered with concerns by many Republicans regarding his stand on abortion, his sanctuary city posture with illegal aliens, his infidelity and divorce, his religious view (or lack thereof), and frankly, there are a lot more attractive candidates out there to consider, like Mitt Romney, Mike Huckabee,and Ron Paul among others. Mitt Romney has done a lot to accentuate the negatives of the Giuliani candidacy and has ignored, until recently the candidacy of Huckabee.