Assuming he doesn't mean willpower, then I beg to differ. I would argue that in fact Congress does have the power, but what they do lack is the will to confront the financial lobby that pays them quite well to look away. Laws and regulations could be passed that significantly curtail the wrongdoings perpetrated by these large firms, however our political system is so riddled with corporate influence nothing with teeth ever gets enacted.
But again, it's not that they don't have the power, it's that they don't have the incentive and/or fortitude to do what's right, and therefore piss off those entities which allow them to remain incumbents.
On a separate topic, I completely agree with Kevin when he discusses how Afghanistan could become a "political nightmare" for Obama:
[W]hat it demonstrates most strongly is the fantastic political nightmare involved in ever pulling out of a war that hasn't been decisively won. Vietnam is the big-ticket example here, of course, but there are better ones. Take Somalia. After the Black Hawk Down incident in 1993, conservatives demanded that Bill Clinton pull out immediately. Not another American life was worth risking for a barren patch of dirt on the Horn of Africa. Clinton refused, insisting that we "finish the work we set out to do," and kept troops in country for another six months before withdrawing in an orderly way.
And what happened? Conservatives turned around and immediately started building up a mythology that Clinton had lacked spine and immediately ran for the exits at the first sign of trouble. Just like a Democrat to be so weak-kneed! What's more, it's now received wisdom on the right that it was this panicky withdrawal that first convinced Muslim fanatics that America was weak and could be attacked with impunity. In the end, Clinton took a hit for withdrawal even though he was the one who insisted on not cutting and running.
If that's what happens to a Democratic president who played a hawkish role in a small, unimportant war, what would happen to a Democratic president who played a dovish role in a big, important war?