By Jon Frandsen, Senior Editor April 28, 2009 For the second time in eight years, Republican insistence on ideological purity has cost in a big way. They lost control of the Senate in 2001 when GOP Sen. James Jeffords of Vermont responded to pressure, threats and political alienation by his party by leaving and joining the Democratic caucus. This time, with no majority left to lose, they have probably provided the Democrats with the 60th vote they need to block GOP filibusters -- the last real tool at their disposal for holding back the Democrats -- by pushing Pennsylvania Sen. Arlen Specter out of the fold.Will the GOP finally get the message that it has ceded the political center to the Democrats, who have proven much more adept at attracting and managing diverse ideologies? Unfortunately for Republicans and the two-party system, probably not. Conservatives who control the party seem perfectly happy to keep applying litmus tests to candidates, making the party's political appeal so narrow that future Republican National Conventions could be booked in a Holiday Inn hospitality suite.For evidence of just how out of touch the party is, look no further than the reaction of much of the party to Specter's announcement. "Senator Specter didn't leave the GOP based on principles of any kind. He left to further his personal political interests because he knew that he was going to lose a Republican primary due to his left-wing voting," said Republican National Committee chief Michael Steele.Bitterness at what is seen and felt as betrayal is understandable, but it doesn't excuse a complete flight from reality. Of course Specter switched parties because it looked likely he would lose the GOP primary -- the party-base in Pennsylvania is shrinking and becoming more conservative all the time. What Steele left out, however, is that Specter had a good shot at winning in the general election as a Republican -- and if he lost it would have been because Democrats persuaded voters he was too conservative. Now Specter may be the one to make the same point in walloping the GOP next year. As far as Specter's "left-wing voting record" goes, tell that to the most reliably liberal institution in the country, labor unions. If Specter had been in danger of losing as a Republican in heavily unionized Pennsylvania's general election, it would have been because he may have cost labor its biggest prize in this Congress -- union card check off, a controversial proposal to circumvent union elections. Specter is vowing not to change that position, but Democrats and union members are bound to be much more forgiving now. His opponent will be a far more serious threat to labor than Specter would ever be. In truth, Specter has a 44.47 lifetime rating from the American Conservative Union, certainly low when compared to most other Republican senators in his party -- but simply soaring when compared to all but a couple of Democrats, who are lucky to break into double digits. But ideological purity is in such high demand in the GOP that it is rapidly approaching the point where it would rather lose a relatively reliable vote (Specter voted with Republicans well over half the time) by defeating a moderate in a primary and then go on to lose a general election to a far more liberal Democrat. How else do you explain the fact that the biggest conservative victories in 2006 and 2008 were not defeating Democrats, but in knocking off moderate Republicans such as Rep. Heather Wilson of New Mexico and Wayne Gilchrist of Maryland in primaries, only to lose in November? The cost to the GOP of this cannibalism -- to use Specter's word -- goes far beyond numbers. Specter cited the conservative challenge of moderate-to-liberal Sen. Lincoln Chaffee, R-R.I., in 2006, which sapped his campaign funds and weakened him considerably in the general election. Chaffee lost that seat, which cost the GOP the majority in the last two years of President George Bush's term. The ramifications of that were huge, but Specter pointed to just one issue -- the judiciary, which ranks as a top concern to conservative Republicans. Dozens of judicial appointments that would have been approved by a Republican Senate died under Democrats. It's pretty difficult to see the conservative principle behind that.Specter left the party with some angry advice: "There ought to be a rebellion, there ought to be an uprising" against the conservative wing of the party. Unfortunately for would-be rebel Republicans, his battle cry left out something crucial: Who's left to lead it?