We've spent the last six weeks speculating what will happen in Pennsylvania. But for all its hype, the April 22 contest, now finally a week away, isn't likely to significantly alter the Obama-Clinton race.

Short of an upset by Obama, which seems unlikely given the pounding he's received over the last five days by Clinton, McCain and the conservative media, the campaign will move on to Indiana and North Carolina on May 6, and on and on from there. Clinton will of course score a PR bounce by winning the Keystone state, but the mathematics of clinching the nomination won't change much. "Clinton, even with a victory in Pennsylvania, would make only a small incremental gain against Obama's overall lead in the delegate race," Congressional Quarterly predicted today.

Obama's lead in pledged delegates remains virtually insurmountable. "[Clinton] isn't going to win at the polls," Jonathan Chait of The New Republic wrote last month in a provocative column. "Barack Obama has a lead of 144 pledged delegates. That may not sound like a lot in a 4,000-delegate race, but it is. Clinton's Ohio win reduced that total by only nine. She would need 15 more Ohios to pull even with Obama. She isn't going to do much to dent, let alone eliminate, his lead."

Based on these numbers, Chait goes on to make the case for why Clinton should exit the race for the good of her party. (Chait's argument, incidentally, has been strengthened by the events of the last week, with Clinton and McCain sharing the same talking points against Obama.)

One's perception of the race still hinges on whether you think the contest is about math or momentum, as Tim Noah of Slate has chronicled. Before Iowa, the press was all about momentum--whomever won the early states would go on to capture the nomination. Three months later, before Ohio, the press was all about math--and Obama's string of victories since Super Tuesday, they concluded, made it impossible for Clinton to win.

After Ohio and Texas, the media doesn't seem to know what to believe, the "arithmecrats" or the "momentucrats," as Noah calls the respective groups. Most political reporters I know privately believe Obama is all-but-certain to be the Democratic nominee, no matter what Clinton does. Yet they continue to cover the contest, in Pennsylvania and elsewhere, as if it's a dead heat.

The math has favored Obama for the past two months and will likely continue to. The momentum swings back and forth. Obama had it after Clinton's Bosnia gaffe and the Mark Penn scandal. Clinton had it after Obama's Jeremiah Wright scandal and small-town gaffe last week. These controversies, real or invented, last for a week or so and then give way to something else.

The momentum impacts the math, particularly when it comes to influencing the votes of superdelegates who continue to (maddeningly) sit on the sidelines. But the math is ultimately what matters, and will decide when this never-ending primary finally comes to a close and that other race, against John McCain, finally begins.

The Nation, April 15, 2008