The power of victory can be inspiring to one's confidence.
Case in point: Hilary Clinton. After appearing to be on the ropes, down and out, ready to concede after a valiant last stand, she has emerged from the primaries in Ohio and Texas rejuvenated and talking boldly about her future prospects. There is simply no other explanation than a serious jolt of confidence that can rationalize her proclaiming that she would be happy to have Barack Obama as her VP candidate. She still trails by over 90 delegate in the race to cinch the nomination, yet she's moving to put Obama on the defensive. It's a brilliant tactic. People latch on to confident leaders. The Clinton campaign will use this boost to propel them for at least two weeks, maybe more if momentum continues to build.
Meanwhile, John McCain can prepare salvos against both candidates, having sewn up his own victory last night. You can rest assured that the Republican machine will spend a lot of time and money crafting messages for both Democratic candidates, unleashing their full arsenal probably well before one candidate emerges.