When political parties sense an imminent defeat, do they nominate "war heroes"?

Clearly if you think McCain is facing imminent defeat, you aren't actually paying attention. Obama is far below where he should be by all accounts. And every time McCain comes out with an ad, Obama loses ground. Meaning, Obama is not tough enough to handle the Republican onslaught. The Republicans defeat should have been imminent but the Democratic party threw away their victory as they do over and over and over again.