Congratulations Scott Brown!

Yah-boo to the defeated Democrats.

But now the challenge returns to the GOP: Can we learn the right lessons from the success in Massachusetts, atop prior wins in Virginia and New Jersey?

Scott Brown may have saved the Republic from a filibuster-proof  Democratic Senate. But let’s remember that it was past Republican mistakes that awarded the Dems that filibuster-proof Senate in the first place. The electorate in 2008 gave the Democrats only 59 Senate seats, counting Bernie Sanders and Joe Lieberman as Democrats. It was the decision by the former president of the tax-cut lobby Club for Growth to mount a primary challenge to Pennsylvania Republican Arlen Specter (and for good measure to give him more than a year’s warning) that prompted the party switch that bumped 59 to 60.

If Scott Brown wishes to win re-election from Massachusetts in 2012, he will likely accumulate a voting record at least as liberal as Specter’s prior to the Pennsylvania senator’s party switch. (After all, Massachusetts has a more liberal electorate than Pennsylvania’s.) Specter accumulated American Conservative Union ratings of 40–60 percent through most of his years in the Senate.

Question: If Brown’s record turns out to be acceptable – why wasn’t Specter’s? Conservative activists gallantly rallied to Brown to save the country from Obamacare. But if the “big tent” spirit that elected Brown had been in effect in 2009, the whole nail-biting, nerve-wracking, down-to-the-wire health-care debate would have taken very different form. Because Specter would not have been pushed into the Democratic camp in the first place.

Can conservatives learn a lesson? The GOP in its majority days was a center-right coalition representing a broad range of views. It was a pro-life party that made generous room for pro-choice social moderates; a tax-cutting party that included those who put budget-balancing first; a hawkish party that kept a place at the table for more conciliatory internationalists. Yes, that old GOP was less ideologically coherent, but majority parties are messy parties.

In more recent years, Republicans have seemed determined to neaten their party by narrowing it. Following Specter’s excommunication, the Club for Growth targeted Utah Republican Sen. Robert Bennett for a primary challenge. (Bennett offended the club by co-authoring a health-reform plan that included an individual mandate to buy insurance.) Similarly, the most electable Republican seeking to fill Barack Obama’s former senate seat in Illinois, Rep. Mark Kirk, has been targeted by a gay-baiting whisper campaign and attacks on his concern for the environment. John McCain’s 2008 election strategy depended on winning Pennsylvania, yet the most popular Republican in Pennsylvania, former Gov. Tom Ridge, was precluded as running mate because of his pro-choice views. Republicans used to have a substantial pro-choice constituency. But no pro-choice candidate has made it on a national ticket since 1976 – sending a message to politically ambitious Republicans in the Northeast and California that their future inside the GOP has a low ceiling.

By contrast, Scott Brown commanded broad enthusiasm throughout the Republican Party, from libertarians to vegetarians, to borrow an old joke of John McCain’s. Does the breadth of enthusiasm bespeak a broadening of accepted views? If so, Tuesday’s big victory offers more than hope for a better quality of health reform. It offers hope that the Republican Party has truly recovered its center – and its way not only to win, but to be deserving of it.