The nomination of a gay black Miami judge to the US federal bench has effectively been blocked after a Republican senator announced he was withdrawing support.

Judge William Thomas, who has served on Miami-Dade Circuit Court since 2005, was nominated by President Obama in July.

Without Florida Republican Senator Marco Rubio’s approval, Judge Thomas’s nomination to the Federal District Court for the Southern District of Florida has no hope of progressing.

Democratic Florida Senator Bill Nelson approved Judge Thomas’s nomination in July. However, Senator Rubio is concerned about Judge Thomas’s actions in two criminal cases – accusing him in one of lenient sentencing.

The New York Times reports in the sentencing case, involving a hit-and-run incident, Senator Rubio’s criticism was rejected by both the lead prosecutor and the 11th Judicial Circuit criminal division.

Senator Rubio also expressed concern over Judge Thomas’s decision to keep out a confession in a murder case involving five defendants in which a young woman was raped and shot dead.

Judge Thomas ruled that two of the defendants in the case, including a 15-year-old, either had not been properly read their Miranda rights or had not understood them.

The ruling was partially supported by an appeal’s court.

“As much as I would like to think that politics has nothing to do with this, it looks as if it does,” said Yolanda Strader, president of Miami’s largest association for black lawyers, who called Judge Thomas one of the hardest working on the bench. “It would be unfair to prevent a well-qualified judicial nominee from proceeding with the nomination process because he is an openly gay black male.”

Had he been confirmed by the United States Senate, Judge Thomas would have become the first black openly gay man on the federal bench.