Like her or not, you have to be impressed by Hillary Clinton's resilience as a candidate. She's been up against the wall at least four times during this campaign, and every time she has come through with exactly what she needs to stay alive. Some Democrats may not appreciate the way she's done it - the New York Times editorial board among them - but on the other hand it's hard to dismiss the kind of guts and determination she's shown as the odds of her winning the nomination have gotten longer and longer.

So is Clinton's 10-point win a "game changer?" Depends on who you talk to, I suppose. Obama supporters and the Obama campaign will argue that nothing has changed: Clinton is still trailing in pledged delegates, trailing in number of states won, and trailing in the popular vote.

Clinton supporters and the Clinton campaign will argue (and in fact already have argued) that last night's vote is an indication the "tide is turning," that Clinton can still catch Obama in the popular vote and, perhaps most importantly, that Obama's failure to "close the deal" continues to raise serious questions about his competitiveness against McCain in the general election.

Assess those respective arguments as you will. They both have certain merits. Obama's case relies on cold hard math. Clinton's case relies on psychology, as Clinton spokesman Mo Elleithee spun to reporters last night: "There is beginning to be a subtle shift of psychology of a lot of the uncommitted supers," he said. We will learn very soon if he's right or not.

In the meantime, Indiana is the new Iowa. With last night's win, Clinton is probably in this thing for the duration, but Obama has another chance to effectively put this contest away in two weeks by winning both North Carolina and Indiana on May 6. On the other hand, if Clinton can hold on in Indiana and somehow upset Obama in North Carolina - where he currently leads in the polls by 15.5% - it could be the true tipping point of the campaign. A split decision on May 6 would mean that the long, hard slog to the Democratic nomination will continue.