WASHINGTON (AP) — Democrats on the Senate Judiciary Committee voted Thursday to authorize subpoenas for two prominent conservatives who arranged luxury travel and other benefits for Supreme Court justices, but Republicans challenged the legitimacy of the move and pledged to withhold support for enforcing the legal order.

The committee chairman, Sen. Dick Durbin, D-Ill., pushed through the vote in the meeting's final moments after Republicans had walked out in protest. The vote from the 11 Democrats would authorize subpoenas for Republican megadonor Harlan Crow and conservative activist Leonard Leo. But without bipartisan backing, the subpoenas probably will not be enforced because that would take 60 votes in the closely divided Senate.

During a contentious committee meeting, Republicans tried to delay the vote before Sen. Lindsey Graham, the committee's top Republican, invoked a rule to limit the session to two hours. Nonetheless, Durbin proceeded with a vote to authorize subpoenas.

"They think we're gonna roll over and come back sometime later and try all over again and face the same limitations," Durbin said. "There reaches a point where there has to be a vote. They walked out on it. That's their decision."

Graham, R-S.C., said later he was ready to "move on" from challenging whether committee rules were followed, but added that ultimately the subpoenas would not be enforced. Leo and Crow issued statements saying the authorization of the subpoenas was not valid.

Crow's office said Crow was willing to engage with the committee, but that Democrats so far "have made intrusive demands of a private citizen that far exceed any reasonable standard and to this date have not explained why this request is necessary to craft legislation."

Leo, a longtime executive with the conservative Federalist Society who has orchestrated a push to move the court and the rest of the judiciary to the right, said in a statement, "I will not cooperate with this unlawful campaign of political retribution."

Crow has had both a close personal and financial relationship with Justice Clarence Thomas for more than two decades. Crow paid for nearly annual vacations for Thomas and bought from Thomas and others the Georgia home in which the justice's mother still lives. He also paid for the private schooling for a Thomas relative.

Democrats are investigating the ethics of the Supreme Court's justices and are seeking information from Leo and Crow on the gifts and trips they gave to Supreme Court justices. Durbin said Leo and Crow have not cooperated with the committee's requests for more information.

"Both Leonard Leo and Harlan Crow are central players in this crisis," Durbin said. "Their attempts to thwart legitimate oversight efforts of Congress should concern all of us."

The high court this month adopted its first code of ethics after facing criticism for the gifts and luxury trips that some justices received from wealthy benefactors. But Democrats pointed out that the ethics code lacks enforcement and allows the justices to police themselves. It "falls far short of what we would expect from the highest court in the land," Durbin said.

The committee has advanced legislation to impose a separate ethics code on the court.

During Thursday's hearing, senators at times rehashed years-old grievances over the tactics used to control a committee that has been central in the political fight over judicial oversight. Republicans, angry at Durbin's attempt to forge ahead on the subpoena vote, threatened that any bipartisan cooperation on the committee would be destroyed.

When Durbin limited debate on separate judicial nominees to prevent Republicans from delaying the subpoena vote, GOP senators threatened retribution.

"You are going to have a lot of consequences coming if you go down this road," said Sen. Tom Cotton, R-Ark.

The committee had previously planned to subpoena another wealthy Republican donor, Robin Arkley II, who arranged and paid for a private jet trip to Alaska for Justice Samuel Alito in 2008. Durbin dropped that subpoena after Arkley provided information the committee was seeking.