The outcome was expected, but that doesn’t change the fact that it was maddening.

Senate Republicans on Monday blocked President Obama’s choice to be ambassador to El Salvador after raising questions about whether her former boyfriend was a spy for Cuba. Republicans also were concerned that Mari Carmen Aponte wrote a commentary about gay pride that offended some citizens in the conservative Catholic country.

Aponte is serving in the post temporarily as a recess appointment that expires at the end of the year. Efforts by the White House and congressional Democrats to defend and promote Aponte to a permanent position fell short when the Senate voted along party lines against her.

To overcome a Republican filibuster, Aponte needed 60 votes. She got 49, including the support of just two Republicans, Maine’s Susan Collins and Massachusetts’ Scott Brown. (Olympia Snowe, who seems to be slipping further and further from reality with each passing day, supported the filibuster.)

As we discussed over the weekend, President Obama gave Aponte a recess appointment in 2010 to serve as the U.S. ambassador to El Salvador, and now the administration wants her to be formally confirmed to the position, at least through 2012. Sen. Jim DeMint (R-S.C.) led the fight to kill the nomination, pointing to Aponte’s ex-boyfriend from 20 years ago, who was accused of having ties to the Castro government in Cuba.

If investigators had turned up evidence connecting Aponte to the Castro regime, then it would certainly be a legitimate issue. If there was any reason to believe Aponte had shared sensitive intelligence with her ex-boyfriend, obviously it would deserve extensive scrutiny. If there was any reason at all to believe Aponte had performed poorly in her job over the last year, Senate confirmation would deserve to be in doubt.

But none of that is true. She has no connections to the Cuban government; she never shared sensitive intelligence with anyone, and didn’t even have top-secret clearance until after she’d broken up with her ex-boyfriend; and by every measure, Aponte has already been doing this job extremely well. The Senate should be thanking her and pleading with her to stay on the job.

But that’s not how Republicans operate in 2011.

What about complaints that Aponte used her office to promote LGBT rights? As it turns out, the ambassador wrote an op-ed essay in a Salvadoran newspaper praising the country for signing a U.N. declaration for the elimination of violence against gays and lesbians. It was part of a State Department initiative urging ambassadors to do something in recognition of Gay Pride Month.

With yesterday’s vote, Aponte, despite excellent work, will have to return home. The dysfunction plaguing the Senate just keeps getting worse.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.