How big of advantage is the "home state" advantage in a primary? Big. A distinction should be drawn between a typical "home state", and Romney's home state of Michigan--which Romney only carried by a few points. Although Romney undoubtedly has ties to Michigan, a more apt comparison would be to Massachusetts, where Romney is better-known and recently served as governor. On Super Tuesday, Romney won Massachusetts with 72% of the vote, beating Santorum by a whopping 60 points. That same day, Newt Gingrich, whose campaign was already in tatters, won his own home state of Georgia with 47%, just over 20 points higher than Romney; other Southern states voting on Super Tuesday were carried by Santorum.
In summary, it ought to be understood that Santorum is starting out with an enormous advantage in Pennsylvania. Indeed, on February 20th (roughly at the height of Santorum's surge), a Franklin & Marshall poll had Santorum ahead by nearly 30 points there. A lot has changed since then, namely Santorum's key defeats in the Midwestern states of Michigan, Ohio, Illinois, and Wisconsin, along with the overall impression taking hold that Romney is inevitable. Still, that's quite a gap to close, and Santorum's campaign is taking an "all-in" approach in Pennsylvania, if only to avenge his infamous senatorial reelection loss. Here are the most recent polls in the state--most of which were taken prior to Santorum's loss in Wisconsin on April 3rd:
Pennsylvania Primary
04/04 PPP (D) -- Romney 42, Santorum 37, Paul 9, Gingrich 6
04/04 Rasmussen -- Santorum 42, Romney 38, Paul 7, Gingrich 6
04/01 Quinnipiac -- Santorum 41, Romney 35, Paul 10, Gingrich 7
03/27 Wenzel -- Santorum 45, Romney 25, Paul 10, Gingrich 8
03/25 Franklin -- Santorum 30, Romney 28, Paul 9, Gingrich 6
Even looking at the two polls taken after Wisconsin, there's quite a bit of variation: One has Romney up by 5, and the other has Santorum up by 4. But the bottom line is that both of those polls are terrible for Santorum. Romney has repeatedly overcome Santorum's early leads of more than 4 points. Santorum is in deep trouble--Pennsylvania is already competitive.
There are some silver linings for Santorum. As his home state, Pennsylvania may choose to reward Santorum's persistence in a last-minute fit of nostalgia. Santorum will also have three weeks to campaign there. And since Pennsylvanians are already familiar with Santorum, Romney's attack ads should have less effect.
But there's one big problem that could trump all that and give Romney the win: Over the next few weeks, the idea that Romney has already won the nomination will sink deeper into the minds of Republican voters. Without victories to sustain the Santorum campaign, potential Santorum voters will be poisoned by the toxic idea that a vote for Santorum simply helps Barack Obama.
Elephant Watcher believes that Santorum could be persuaded to quit the race early if he loses in Pennsylvania, or if the early Pennsylvania polls are bad enough to convince Santorum that he's going to lose there. Right now, the picture is bleak, but it's not yet certain Santorum will lose.
