Karl Rove, the Republican strategist behind President Bush's victories in 2000 and 2004, gives Obama 311 electoral votes to McCain's 157, with 70 electoral votes in the tossup category.
The tossups are all in states that Bush carried the last time, including Florida, Missouri and North Carolina. McCain trails in six other states Bush won in 2004: Virginia, Ohio, Iowa, Colorado, New Mexico and Nevada.
If McCain carries every tossup state plus Virginia and Ohio, which one of his top aides calls the toughest battleground for the Republican, he would still be 10 electoral votes short of 270. That would require him to pick up either Pennsylvania, where he has never led in the general election, or two other Bush states where he is behind.
For McCain to move that many states in a short period of time, strategists said, would likely take an unexpected event of major proportions. The only time in recent history that a late change in voter sentiment put the trailing candidate into the White House was in 1980, when the lone debate between President Jimmy Carter and Ronald Reagan, a week before the election, vaulted Reagan into office.
"It looks like we're going to come up short," said Scott Reed, a McCain supporter who managed Bob Dole's 1996 presidential campaign.