Lincoln Mitchell in The Huffington Post:
Throughout his presidential campaign, but more notably, during his presidency, President Obama has shown himself to have an impressive ability to accumulate political capital. During his tenure in the White House, Obama has done this by reaching out to a range of constituencies, moderating some of his programs, pursuing middle of the road approaches on key foreign policy questions and, not insignificantly, working to ensure that his approval rating remains quite high.
Political capital is not, however, like money, it cannot be saved up interminably while its owner waits for the right moment to spend it. Political capital has a shelf life, and often not a very long one. If it is not used relatively quickly, it dissipates and becomes useless to its owner. This is the moment in which Obama, who has spent the first few months of his presidency diligently accumulating political capital, now finds himself. The next few months will be a key time for Obama. If Obama does not spend this political capital during the next months, it will likely be gone by the New Year anyway.