Barack Obama is running for President. Or at least seriously, seriously, thinking about it.

He conceded as much on Meet the Press yesterday. “I don’t want to be coy about this,” Obama told Tim Russert, “Given the responses that I’ve been getting over the last several months, I have thought about the possibility, but I have not thought about it with the seriousness and depth that I think is required.”

A pretty frank admission, after months (or years) of flattering media coverage. But why hint at a possible candidacy now, in advance of the midterm elections? Is he just trying to sell his new book, The Audacity of Hope? Or is there another possibility: Obama’s hoping to push Hillary Clinton out of the race. Also on Meet the Press, Wall Street Journal reporter John Harwood said a former top Clinton Administration aide told him Obama would run and Hillary wouldn’t.

If they both run, the election becomes Obama versus Hillary and then everyone else. If Hillary doesn’t run, it’s Obama versus everyone else.

Is the Democratic primary big enough for an Obama and two Clintons?