Barack Obama started in on that during a round of phone calls to Pennsylvania radio stations on Monday, tacitly admitting that he won't win, but that he should keep the race close.

"I'm predicting it's going to be close and that we are going to do a lot better than people expect," Obama told KDKA-AM in Pittsburgh.

Let's start with the basics - if Obama wins in Pennsylvania, this race is over. He is the nominee.

If Clinton wins by 5 or less points, that spells big trouble for her. I would expect big shot Democrats to immediately come out and publicly urge her to get out of the race.

The grey area is a Clinton win between six and nine points. That's a solid win, but the Obama people will certainly argue that anything less than double digits is not enough.

Realistically, Hillary Clinton needs a double digit win to advance - with no questions about her candidacy - to the next round of primaries on May 6 in North Carolina and Indiana.

The Clinton people meanwhile were doing their best to flip the expectations game back at Team Obama, saying a loss for Obama in Pennsylvania would show that he is not the best candidate for Democrats in a November matchup with John McCain.

"What is true about the general election is that historically the people most likely to be swing voters are the kinds of voters that Sen Obama has had his greatest problems with," said chief Clinton strategist Geoff Garin.

Those voters are mainly blue collar and middle income voters - the Reagan Democrats for lack of a better shorthand description.

Watch the results out of central Pennsylvania to get an idea of how Obama is doing with those voters. Those more rural counties should definitely be a plus for Clinton.

One sure fire indicator about who is going to win this race comes from the Obama schedule on Tuesday. He is not sticking around Pennsylvania for a Primary night celebration.

Instead, he will surface in Indiana for a rally there. Indiana votes two weeks from today.

"I hold out hope for some kind of shocker," one of the reporters on the Obama bus just said as we wait for Obama to speak.

We don't have to wait long to go from "expectations" to "results."