...I really don't know the answer to that one yet...ask me in November. From the AP:
Republicans are no longer underdogs in the race for the White House. To pull that off, John McCain has attracted disgruntled GOP voters, independents and even some moderate Democrats who shunned his party last fall. ...Partly thanks to an increasingly likable image, the Republican presidential candidate has pulled even with the two Democrats still brawling for their party's nomination, according to an Associated Press-Yahoo news poll released Thursday. Just five months ago—before either party had winnowed its field—the survey showed people preferred sending an unnamed Democrat over a Republican to the White House by 13 percentage points. ...
Of those who have moved toward McCain, about two-thirds voted for President Bush in 2004 but are now unhappy with him, including many independents who lean Republican. The remaining one-third usually support Democrats but like McCain anyway.