McCain campaign strategists, citing internal polling, say that Obama is showing broader weaknesses in the larger electorate.
"We're seeing that in state after state, Obama has trouble drawing beyond his own base. His coalition has been secular liberals, young people and blacks. That's proven to be enough in the Democratic primaries, but he's going to have to go beyond that to win the general election," said Frank Donatelli, the McCain campaign's chief liaison at the Republican National Committee.
"He's done poorly in the past two months in every contest he's run outside of those areas," said the former Reagan White House political director.
The strongest manifestation of Obama's problems in the larger playing field is becoming visible among white blue-collar workers in Midwestern and Southern battleground states.
Consider the recent matchups between the two prospective nominees in a Quinnipiac poll in two key swing states that Democrats must carry.
In Ohio, a Democratic-leaning swing state in much economic distress, McCain edges ahead of Obama by 44 percent to 40 percent. In Florida, a state that Democrats are heavily targeting, McCain led by 45 percent to 41 percent.
"Obama is losing the white vote by 14 to 18 points in Ohio and Florida, which is enough to keep him from victory despite overwhelming support from African-Americans," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute.
McCain strategists readily acknowledge the economy and the war in Iraq posed major political obstacles, but Donatelli says they are convinced that the election will to a large degree turn on "the blue-collar workers in the Midwest." These are the old Reagan Democrats, and they are in play more than at any time since Reagan, despite the downbeat economy.
"Obama is a cultural and social liberal, and he has trouble connecting with these voters. That puts in play a number of blue states McCain has a strong chance to win, including Michigan, Wisconsin, Minnesota, Ohio, Missouri and Pennsylvania," he said.
"We feel much better about our chances to win many of the big industrial states in the Midwest," he told me.
Throw in a midyear economic recovery and further troop withdrawals in Iraq by September, and John McCain's chances could look very good, indeed.