WASHINGTON -- The White House has thrown in the towel in trying to confirm William Thomas to a federal court seat in Florida, signaling an end to a puzzling case of Sen. Marco Rubio (R-Fla.) blocking his own judicial nominee.

In a pile of about 200 nominees President Barack Obama resubmitted to the Senate at the start of the year, Thomas was noticeably absent. An administration official confirmed Tuesday that his resubmission isn't coming.

"The nomination of Judge William Thomas was returned by the Senate and Senator Rubio has made his objection clear, so the President chose not to renominate him," the official told The Huffington Post.

Thomas would have made history, if confirmed, as the first openly gay black man to serve as a federal judge.

Rubio has been single-handedly blocking Thomas for months, despite recommending him to Obama in 2012 as a nominee to the U.S. District Court for the Southern District of Florida. Rubio indicated in September he would not submit his "blue slip" to the Senate Judiciary Committee -- a courtesy, but not a hard rule, honored in the committee that allows a home-state senator to advance or hold up a nominee. Florida's other senator, Bill Nelson (D), submitted his blue slip months ago.

Sen. Patrick Leahy (D-Vt.), who chairs the Senate Judiciary Committee, has hinted in the past that he would revisit the blue slip process if Republicans abuse it. Asked for his thoughts on the White House sinking Thomas' nomination after Rubio used the blue slip rule to block him, Leahy said only, "Let me find out about that one."

There's a particular urgency to filling this Florida judgeship, which has been vacant for more than 20 months. The court backlog is so bad that the Administrative Office of U.S. Courts has deemed it a “judicial emergency."

Rubio spokeswoman Brooke Sammon said Tuesday she had nothing new to say regarding why Rubio became so adamant about blocking Thomas. She pointed to a past comment on the senator's concerns with the nominee.

"The nomination of Judge Thomas has also been thoroughly reviewed, and Senator Rubio has determined that Thomas’s record on the state court raises serious concerns about his fitness for a lifetime federal appointment. Those concerns include questions about his judicial temperament and his willingness to impose appropriate criminal sentences, particularly in the two high-profile cases of Michele Traverso and Joel Lebron last year. After reviewing Thomas’s record, Senator Rubio cannot support moving forward with the nomination," Sammon said.

HuffPost previously reviewed materials provided by Rubio's office that outlined the senator's justification for sinking Thomas' nomination, and nothing egregious stood out in either of the two cases. Instead, Rubio appears to be critical of Thomas for being too lenient in one case and too emotional in the other.

Florida Democratic lawmakers say Rubio's opposition is political as he tries to win back support from tea party members after angering them by advocating comprehensive immigration reform in 2012. Rubio's name has also been floated as a potential 2016 presidential contender.

"Judge Thomas is a well-qualified jurist," Rep. Alcee Hastings (D-Fla.) told HuffPost in the fall. "There is a serious underrepresentation of minorities on the bench and partisan obstructionism isn’t making it any better."

Hastings is a member of the Congressional Black Caucus, which has railed against Rubio for blocking black judicial nominees at a time when the group says black judges make up about 8.3 percent of the federal judicial bench. In addition to Thomas, Rubio had been withholding his blue slip for another black judicial nominee, Brian Davis. But Rubio ultimately agreed to move forward with Davis, who has since been confirmed.