Kirsten Gillibrand has, up to this point, been very lucky. With her powerful guardian angels Chuck Schumer and Barack Obama watching over her, countless Democrats mulling a primary run have been convinced to sit this one out. High-profile, big-name Republicans like Rudy Giuliani and Peter King have bowed out on their own. For someone considered so vulnerable -- an appointed senator, still largely unknown, with a malleable ideology -- it's almost a miracle for Gillibrand that nobody has stepped up to the plate yet. But that doesn't mean there aren't still plenty of possible challengers waiting in the wings, and Harold Ford Jr. is only the most vocal and visible one. But who among them will actually enter the race, and who actually poses a threat to Gillibrand?