Senate Democrats officially launched their third filibuster of a judicial nominee Thursday, with a fourth blockade set to start Friday, as both sides continue to trade charges of religious bias in their handling of the nominating process.

By a 53-44 vote, Republicans came up short of the 60-vote threshold required to invoke cloture on the circuit court nomination of Alabama Attorney General William Pryor. All Republicans and two Democrats, Sens. Zell Miller (Ga.) and Ben Nelson (Neb.), supported the motion to end debate and move to a vote, with 44 Democrats opposed.

Sen. Jim Jeffords (I-Vt.) did not vote, and two Democratic presidential contenders, Sens. John Kerry (Mass.) and Joe Lieberman (Conn.), also missed the vote.

Majority Leader Bill Frist (R-Tenn.) has set a cloture vote for Friday on the circuit court nomination of Los Angeles County Superior Court Judge Carolyn Kuhl, to the 9th U.S. Circuit Court of Appeals, who is likely to meet a fate similar to Pryor’s. Earlier this week Democrats continued their blockade of two other circuit court nominees, former U.S. Assistant Solicitor General Miguel Estrada and Texas Supreme Court Justice Priscilla Owen, who lost their seventh and third bids for cloture, respectively.

Pryor and Kuhl are both practicing Catholics who hold socially conservative personal views in line with some of the church’s teachings, an issue that has been put front and center by Senate Republicans and an independent conservative group that has placed newspaper ads accusing Democrats of bias against religious Catholics.

Calling Pryor “the kind of guy you want your sister or daughter to marry,” Sen. Lindsey Graham (R-S.C.), a Baptist, said many religious people who have deeply held personal views would be blocked from the federal courts under the Democratic standard, no matter how many times the nominee promised to uphold the law regardless of his or her personal views.

“If he can’t be a judge, I can’t be a judge, because I share many of those values and beliefs,” Graham said at a press conference following the cloture vote, where he was joined by religious experts and leaders of several faiths.

But Democrats contend it was Republicans, along with their conservative allies at the Committee for Justice, who first injected religion into the Pryor and Kuhl nominations. The committee placed ads in Maine and Rhode Island newspapers — targeting the support of GOP Sens. Lincoln Chafee (R.I.), Susan Collins (Maine) and Olympia Snowe (Maine) — that had a dark and foreboding picture of a fake courthouse with a sign out front reading “Catholics Need Not Apply.”

At Pryor’s nomination hearing to a seat on the 11th U.S. Circuit Court of Appeals before the Judiciary Committee, Chairman Orrin Hatch (R-Utah) specifically asked Pryor: “OK, now just for the record, what is your religious affiliation?”

“I’m a Roman Catholic,” Pryor responded, prompting Hatch to ask, “Are you active in your church?”

“I am,” Pryor said, leading Hatch to “commend you for that.”

Sen. Patrick Leahy (D-Vt.), ranking member of the Judiciary Committee, tried to offer a resolution Thursday that would change chamber rules and forbid any Senator from asking such a line of questioning again at a nomination hearing, but he could not get unanimous consent.

At a press conference after the vote, Minority Leader Tom Daschle (D-S.D.), a Catholic himself like Leahy, excoriated Hatch’s questioning. “I hope that we never see this practice used again,” he said.