CBS News Senior White House Correspondent Bill Plante says McCain's chief pollster, Bill McInturff, asserts the race may be too close to call by Election Day Tuesday if McCain's numbers improve in the four key states where he's been stumping nonstop.
"John McCain has got to win Ohio and Florida, and we have to, we have to carry Virginia or Pennsylvania; hopefully, both," McInturff says.
At the moment, Plante points out, most polls have Obama ahead in the battleground states. But McCain is counting on two things.
One: undecided voters.
"I wouldn't be surprised if, at the end of the day, the more than half of the undecided voters, the moveable voters, do shift to John McCain and we see something slightly narrower than we're seeing today," observed CBS News Director of Surveys Kathleen Frankovic.
McCain is also counting on what pollsters call the "margin of error."
Take Florida, for instance, Plante suggests. The latest Associated Press poll shows Obama ahead by two points, 45 percent to 43 percent. The margin of error in that poll is four points.
That means McCain could be leading there by as much as 47-41, and could easily take the Sunshine State if he gets enough undecided voters to go his way.
Same thing in Ohio. The AP poll has Obama seven points ahead, 48-41, with a four point margin of error. That could mean a virtual tie, McCain 45, Obama 44.
So, Plante asked pollster Mark Mellman, "Is there a chance McCain could pull it out, given the poll numbers?"
"Well," Mellman responded, "there's also a chance that someone could walk up to me on the street and give me a million dollars. Neither of them is very likely."
And Plante says the margin of error, of course, works both ways and, should it work in Obama's favor in Florida or Ohio, he'd have a very big lead.
One last note: The Weekly Reader election survey of students has accurately predicted 12 out of the last 13 elections, making it one of the most reliable polls. On Wednesday, the publication released the results of its 2008 student survey. Obama got 54.7 percent of the student vote to McCain's 42.9 percent.