Earlier this month, the White House returned to the Senate 54 federal judicial nominees who Senate Republicans had refused to vote on in the previous year. But one nominee was conspicuously absent from that list: Judge William Thomas, a Florida state judge who had been nominated to sit on a federal trial court.

At first, Thomas’ nomination seemed like a slam dunk: He is an experienced, respected judge who was nominated in 2012 with the support of both of Florida’s senators, Democrat Bill Nelson and Republican Marco Rubio. He also would have been the first openly gay black man to sit on the federal bench.

Then, mysteriously, Rubio changed his mind. Taking advantage of a Senate Judiciary Committee policy that allows any senator to block a committee hearing on any nominee from his or her home state, Rubio unilaterally refused to allow a hearing on Thomas. For months, the senator refused to explain why he was blocking Thomas’ nomination, until finally this summer a spokesperson cited “questions about [the nominee’s] judicial temperament and his willingness to impose appropriate criminal sentences.”

Rubio’s office provided two examples of instances in which they believed that Thomas didn’t impose “appropriate criminal sentences.” In both cases, Thomas imposed the highest sentence sought by the prosecution; in both cases, prosecutors praised his handling of the trials. Rubio’s staff also claimed that in one of those cases, a grisly murder trial, Thomas “broke down in tears” when sentencing the defendant to death; news reports make clear that the judge’s tears came when he was describing the brutal crime. As Chris Hayes put it, none of these complaints “pass the smell test.”

Now, finally, Rubio himself has gone on the record for the first time about why he blocked Thomas’ nomination. In an interview with Michael Putney, political reporter for the Miami-area Local 10 news, Rubio, looking visibly uncomfortable, repeats his office’s talking points about the two criminal cases they allege Judge Thomas imposed insufficiently harsh sentences in. “We are looking for judges that can accurately apply the law, particularly at the federal level,” Rubio said, never quite explaining how Thomas failed to do that.

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This isn’t the first time that Rubio has blocked a Florida judicial nominee for less than convincing reasons. Rubio similarly changed his mind about Florida nominee Brian Davis – who is also African-American – at the behest of Sen. Chuck Grassley . Under pressure from local activists, Rubio eventually changed his mind again and allowed Davis’ nomination to go forward.

As Hayes said, it seems like the most likely explanation is that Judge Thomas was merely an “innocent bystander” in Rubio’s desperate race to win back the right-wing support he lost during his short-lived advocacy for immigration reform – an effort that so far isn’t panning out so well.