On what grounds? The American People are the ones that vote. The same people who thought Barry Goldwater would blow up the world and LBJ would ensure peace in 1964, the people who decided that Richard Nixon would bring law-and-order to the country in 1968, the same people who deemed WW2 hero George McGovern to be a dope-smoking pacifist hippie in 1972, the same people who were led to believe that another WW2 hero was a wimp in 1988, the people who in 2002 AND 2004 decided that a political party was actually in cahoots with al Qaeda. There is no gurantee that this country will not decide that Obama is a Muslim, or will enslave all white people, or some other bullshit because we've already proven ourselves quite capable of voting with all the intelligence of a sack of dry cement.
Polls already indicate that the American Voter believes that McCain will be the better commander in chief & will be better in Iraq, despite his not knowing a goddam thing about the situation there, the history, or the people involved. Basically, this country is indicating that they would go with the political/military equivalent of depositing their gambling money with a bookie that doesn't know the difference between the Green Bay Packers & the Chicago Bears.