President Bush and congressional Republicans are orchestrating a full-court press on Senate Democrats, trying to get them to act on two of the president's judicial nominations that have been waiting for confirmation for two years.

On Friday, Bush revived a 6-month-old plan aimed at putting a time frame on filling judicial seats. On the Senate floor, Majority Leader Bill Frist, R-Tenn., (search) introduced a proposed rule change that would bypass the filibuster procedure. 

Two of Bush's judicial nominees have been prevented from getting a simple majority vote because of the use of filibusters -- a procedure used to block a straight up or down vote by requiring 60 votes to end debate on a topic. Senate Republicans have tried a total of eight times to end the filibusters on lawyer Miguel Estrada (search) and Texas Supreme Court Justice Priscilla Owen. 

"Filibustering nominations is a relatively new phenomenon even as to the nominees for the executive branch, and it has emerged in this Congress as a particular problem relative to judges," Frist said. "Without filibuster reform, a disciplined minority can cast an ever-lengthening shadow over the nomination process."

But Senate Minority Leader Tom Daschle, D-S.D., responded that the filibuster tool is one that Republicans have employed in past years.

"I know that some of my colleagues have lamented this notion that filibusters could be employed," Daschle said. "I find it interesting that the majority leader is one of those who voted against cloture" [during confirmation of a Clinton nominee in the 106th Congress]. "He apparently felt at the time that cloture was appropriate."

Under the Frist plan, the first vote to break a filibuster would need the support of 60 senators -- the second 57, the third 54 and the fourth 51. The entire process would take about 13 days. Six times members have voted to end debate and confirm Estrada, reaching a highwater mark of 55. Owen's filibuster has tried to be broken twice, with 52 members supporting her.

GOP sources say Sens. Joe Lieberman, D-Conn., and Tom Harkin, D-Iowa, supported a proposal similar to Frist's and advanced by Democrats during the Clinton administration. Frist's office said Sen. Zell Miller, D-Ga., is in favor of the rule change.

However, to pass the rule would require 60 votes. Republicans say they are not confident they have support for the change.

Friday marks two years since Bush nominated 11 nominees to the appeals courts. Three are still awaiting action and two have been filibustered -- Owen, nominated to the 5th Circuit Court of Appeals and Estrada, chosen for the D.C. Circuit Court of Appeals.

"As of today, three of that original group have waited three years. Their treatment by a group of senators is a disgrace," Bush said in a Rose Garden event. 

"Never before has there been a successful filibuster to prevent an up or down vote on an appeals court nominee. This is an unprecedented tactic that threatens judicial independence and adds to the vacancy crisis on our courts, and it is wrong," he added.

"The Senate has a constitutional responsibility to hold an up or down vote."

Bush returned to a proposal he offered last fall that would demand that judges on the federal appellate and district courts notify the president of their intentions to retire at least a year in advance whenever possible.

The president would then submit a nomination to the U.S. Senate within 180 days of receiving notice of a vacancy or intended retirement. The Senate Judiciary Committee (searchwould hold a hearing within 90 days of receiving that nomination and the full Senate would vote on a nominee no longer than 180 days after the nomination is submitted.

"This plan would apply no matter who lives in the White House or no matter which party controls the United States Senate," Bush said.

But it seems unlikely that Democrats will come around. Daschle said Democrats have blocked only two presidential judicial nominees out of 124 nominations. Democrats have not ruled out filibustering other nominees who come to the floor.

Daschle said the filibusters on Owen and Estrada are for good reason, arguing that the two candidates are particularly conservative and would add to the weight of a federal bench that has tilted conservative as a result of appointments made during the Reagan and first Bush administrations.  

Republicans say the use of a filibuster is unconstitutional because the Constitution does not specifically call for a two-thirds majority vote for a nominee, and usurps the power of the president as well as the Senate's functioning.

"Clearly, we have entered upon a new era damaging to the Senate as an institution, where a majority will be denied its right to consent to a nomination because a minority will filibuster to hold that nomination hostage. The need to reform the filibuster on nominations is obvious and it is now urgent," Frist said.

Fox News' Wendell Goler and Carl Cameron contributed to this report.