"Her biggest challenger is actually Barack Obama. Where his legacy ends is going to reflect on her," she said. "Right now, the president has had a series of what are perceived as foreign policy missteps. If Barack Obama's foreign policy is perceived as having not been successful there will be more questioning about her tenure there."
"Hillary Clinton does have quite an extraordinary past of public service and general political engagement, but how much brighter can her star burn? To a certain extent, I think her greatest challenge is this sense of inevitability and supernova reputation that she's acquired over the last few years," said Lara Brown, program director at George Washington University's Graduate School of Political Management.