Democrats are hoping that the Romney campaign’s decision to invest both time and money in Pennsylvania the last weekend before the election is a sign that the GOP is doomed. Memories of John McCain swooping into the Keystone State four years ago in a futile attempt to gain ground in a state that he would lose by better than 10 percentage points encourages Democrats who believe Romney is making the same mistake. But that was then, and this is now.

Though Romney must still be considered a heavy underdog in Pennsylvania, there’s little doubt that the race has tightened and that a Democratic victory there is no longer a foregone conclusion. Moreover, the Obama camp’s assumption that Romney’s move is rooted in a desperate attempt to craft an Electoral College majority without Ohio may also be dead wrong. Far from conceding the key tossup states to Obama, Romney may be sensing an opportunity to win states few thought he had a chance to take only a few weeks ago.

Conflicting poll numbers in the battleground states have made this one of the most confusing elections in memory. If you believe polls with samples that are disproportionately Democratic then the president seems likely to take Ohio as well as Virginia, virtually closing off any path to 270 Electoral College votes for Romney. But the Romney campaign thinks these numbers are off, since they see little likelihood that the Democrats can conjure up a turnout that will match or even exceed their 2008 hope and change wave that swept Obama into the White House. If, as the Republicans believe, the enthusiastic GOP turnout effort will match that of a Democratic campaign that can’t recapture the spirit of Obama’s first presidential run, Romney is a cinch to win Virginia and has a better-than-even chance in Ohio.

Far from the panic and desperation that characterized the last days of the McCain campaign, the Romney effort right now seems confident not only of winning their share of the tossups but of stealing some blue states on Tuesday. That shone through even in a New York Times story published this morning that reported the shift to the GOP:

But there is a tangible sense — seen in Romney yard signs on the expansive lawns of homes in the well-heeled suburbs, and heard in the excited voices of Republican mothers who make phone calls to voters in their spare time — that the race is tilting toward Mr. Romney.

If ever there were a place where a last-ditch torrent of money could move the needle, this is it. For the last couple of months, there has been a void of presidential ads in Pennsylvania. So when Republican strategists looked for places where their money could go the furthest, they set their sights here, reasoning that a dollar spent in Erie or Altoona would have a greater impact than in a place like Las Vegas or Cleveland, where political commercials have clogged the airwaves.

Despite their bravado, Democrats know Romney is making inroads among women and Jewish voters. Those are demographic groups that fueled Obama’s landslide in Pennsylvania four years ago but which now are deserting him.

Democrats may want to believe that they have Ohio in the bag and that they are in no danger of losing Pennsylvania or Wisconsin, another state where polls show Romney seems to have a real chance. But the decision to have both Romney and runningmate Paul Ryan visit Pennsylvania this weekend seems rooted more in confidence than in a forlorn “Hail Mary” pass to snatch victory from the jaws of defeat. The Republicans may be mistaken in thinking they have any sort of chance in Pennsylvania because of the strength of the Democratic machine in Philadelphia and its still potent ability to manufacture majorities that can outweigh what happens elsewhere in the state. But there is no doubt that state, as well as several others that the Obama campaign had hoped to have wrapped up this late in the game, are still very much in play.