In today’s New York Post, COMMENTARY magazine contributor Abby Wisse Schachter writes about the voters’ “revolt in Pennsylvania,” as conservative Republican Pat Toomey now leads incumbent and newly minted Democrat Arlen Specter by a 45-to-31 percent margin in the latest Franklin & College poll. Given the rising tide of dissatisfaction with President Barack Obama and the Democratic-controlled Congress; the cynical Specter party switch may turn out to have been in vain.

Interestingly, Schachter quotes former Republican Senator Rick Santorum (who backed Specter against Toomey in the 2004 GOP primary, which the latter lost by a whisker) as advising Toomey to stick to the economy while continuing his campaign in the coming months. He’s right about that but given the way his own career in the Senate ended in a landslide loss to lackluster Democrat Bob Casey, Jr. in 2006, Santorum is probably the last person Toomey should be listening to. Nevertheless, Santorum’s rise and fall provides an interesting set of lessons for Northeastern Republicans.

• Good Timing is Crucial: Santorum was first elected to the Senate in 1994, the year of the GOP Congressional avalanche led by Newt Gingrich. He lost his seat in 2006, the year the Democrats took back both houses of Congress. If, as it seems to be the case today, 2010 will be a big Republican year, Toomey’s got this point nailed.

• Be Fortunate in Your Opponents: In 1994, Santorum beat Harris Wofford, an old-time New Deal Democrat who didn’t excite voters in a year when being the incumbent didn’t help. In 2000, when Santorum won an easy race for re-election, he faced conservative Democrat Rep. Ron Klink. Besides an unfortunate name and no statewide appeal, Klink was intensely disliked by his party’s liberal base. Toomey has this category in his favor too. Specter has the burden of being an incumbent who also lacks an enthusiastic base, since most Democrats are less than thrilled about backing a turncoat whose cynicism is legendary.

• Don’t Let Your Opponent Brand You as an Extremist: In 1994, both Santorum and Wofford were able to say that their opponents represented their party’s hard-liners. Neither was able to capture the center but in a Republican year Santorum won a narrow victory. In 2000, after six years of doing his best to portray himself as a politician more interested in serving his constituents than in ideology, Santorum was immune to the Democratic strategy of branding him as an extremist. But by 2006, after a second term during which he acted as if the audience he cared most about was his party’s base as he maneuvered for a possible future run for the White House (an ambition that, believe it or not, he still seems to harbor), the Democrats were easily able to label Santorum as the embodiment of the Conservative Christian movement. This is a potential danger for Toomey as he is every bit the social conservative Santorum was. But as a relatively fresh face on the statewide level, Toomey has the chance to show voters what he cares most about: free market economics. Being pro-life isn’t the kiss of death in Pennsylvania — many Democrats, including the man who beat Santorum in 2006, are against abortion — but coming across as a rigid extremist is fatal.

• Stick to Your Principles: Voters respect a candidate who sticks to his guns even if they disagree on some issues. In 2006, as a two-term incumbent who had become part of a Senate leadership that had presided over a vast expansion of federal spending, Santorum was no longer able to portray himself as a principled conservative on economic issues. Toomey has built all his campaigns for office on opposing not only more taxes and spending but also the whole system of patronage and earmarks by which politicians have always bought the votes of their constituents. In a year in which anger at government is again at a fever pitch, Toomey is perfectly positioned to run against Arlen Specter, whose whole career has been built on the existing corrupt system.

Thus, while Pat Toomey is right to welcome Santorum’s belated support, the latter’s best advice would be “do as I say, not as I did.”