The return of Sen. Arlen Specter to the Democratic Party (he flipped in 1965 from “Kennedy Democrat” to Republican) is something that should be celebrated by Republicans, at least those who are proud to call themselves conservatives. Specter is a career politician whose first priority is himself.

Specter, whose predictable lament that the GOP is not the “big tent” he had been led to believe it was, now embraces a Democratic Party that is an even smaller tent. How many pro-life Democrats exercise any influence in that party? How many opponents to same-sex marriage are in the Democratic leadership? Smaller government? Lower taxes? No leading Democrat, inside or outside Congress, subscribes to such things. And yet the big media and many pundits continue the fiction that Republicans are in electoral trouble because they do not tolerate liberal ideas.

The day Democrats embrace those holding conservative ideas and implement at least some of them will be the day Republicans can be told to water down their principles. In fact, Republicans in recent years have behaved more like Democrats than Republicans and have paid the electoral price for doing so. The major difference between Republicans and Democrats these days is this: Democrats know how to use power when they get it; Republicans, when they gain power, spend most of their political capital trying to prove they are not mean, uncaring, racist, sexist and homophobic. Republicans masquerade as Democrats and want to be liked. Democrats live to rule.

The Republican Party, much to the consternation of conservatives, saved Specter’s bacon in the 2004 election. Part of Karl Rove’s strategy was to re-elect Republicans, no matter how liberal. Specter won that election thanks to the efforts of the Bush White House and gobs of Republican National Committee money that was poured into his race. How sharper than a serpent’s tooth it is to have a thankless politician.

Specter switched parties because of the serious primary challenge he faced from conservative Pat Toomey. As recently as six weeks ago, Specter told The Hill newspaper that he would not become a Democrat because the country needs a vibrant two-party system. What happened? In a news conference, Specter acknowledged that poll data showed he would lose the primary to Toomey. He also said he was promised financial help by Pennsylvania Democratic Governor Ed Rendell should he convert.

The Republican Party is better off without Specter who, along with other “moderates,” has weakened the party. These RINOs (Republicans in name only) have kept the party from renewing its conservative roots and contrasting itself with the liberal wing of the Democratic Party.

Liberals do not win elections for Republicans. Conservatives win elections. Whenever conservatives try to placate liberals and show how sensitive and caring and in touch with the feelings and concerns of the other party they are, they lose. But when Republicans stand on principles and demonstrate conviction and give evidence that their ideas work, they win.

Yes, Arlen Specter kept his word not to let his pro-abortion views get in the way of the confirmations of Justice Sam Alito and Chief Justice John Roberts. In return for that promise he was allowed to remain chairman of the Judiciary Committee. That was a triumph, not of Specter’s conviction, but of pragmatism.

Too often, Republicans play for good reviews from those who hate them and wish to defeat their policies. Good riddance to Specter. The Republican challenge now should be to focus on what works, not ideology, though ideology should drive successful policies.

Specter’s self-serving switch ought to make it easier for the GOP, but will it?

Cal Thomas is a syndicated columnist and author.