A judicial standoff between President Bush and Senate Democrats is slowly nudging a traditionally conservative appeals court to the left, intensifying an election-year argument over the future of the judiciary.

In Bush’s first term, eight Republican-nominated judges and five selected by Democratic presidents occupied the 15 lifetime seats on the Richmond, Va.-based 4th Circuit Court of Appeals, which covers disputes in Maryland, North Carolina, South Carolina, Virginia and West Virginia. Now there are five vacancies on the court, and the 10 seats are split evenly between Democratic and Republican appointees.

The vacancies on the court — if they remain unfilled — are about to have an impact on national policy and this year’s political debate.

In the coming weeks, the court will decide whether to levy a blow to the Bush administration’s policies on legal rights for terrorism detainees in a case involving whether Ali al-Marri, who was designated an enemy combatant by the United States, has the constitutional right of habeas corpus. The court’s current 50-50 partisan split reduces the chances that the Bush administration will win the high-profile case, court watchers say.

To coincide with these decisions, Senate Republicans plan to initiate a fresh push to drum up pressure on the Judiciary Committee to take up the stalled nominees who — if confirmed — would likely ensure that the court stays conservative for years to come. Republicans say their push to break the logjam would elevate an issue that could spill onto the campaign trail, generate enthusiasm from their base and give the GOP presidential nominee, Sen. John McCain (Ariz.), a chance to win over skeptical conservatives.

“This would be a great opportunity for McCain to demonstrate leadership on an issue that is very near and dear to the base,” said Curt Levey, executive director of the conservative Committee for Justice, a group that supports Bush’s judicial nominees.

The president last week invited his nominees to the White House, where he called the delay in action on the 4th Circuit nominees “irresponsible.” Bush says the Senate should confirm at least nine more appellate court nominees before the end of the Congress to match the number of judges confirmed in the final year of the previous two administrations; since the beginning of the 110th Congress, the Senate has confirmed six of his appellate nominees.

Democrats and their allies off Capitol Hill say the Bush administration is intentionally picking a fight by floating nominees certain to face stiff opposition in the upper chamber, rather than making consensus choices that could more easily be confirmed to the bench. They also say Bush has made the problem of vacancies worse by not sending up names quickly enough. Nineteen open positions throughout the federal judiciary have no nominees.

“If President Bush were very serious about filling vacancies, he would nominate mainstream conservatives who might well be confirmed,” said Judith E. Schaeffer, legal director for the liberal People for the American Way. “Instead, he’s shown that he’s motivated by the extreme right wing of the party.”

Judiciary Committee Chairman Patrick Leahy (D-Vt.) defends his panel’s work, saying that the Senate confirmed more nominations in 2007 than it did in the preceding three sessions when Republicans ran the chamber.

But the fact that the committee has yet to schedule any hearings over the 4th Circuit nominees is only likely to exacerbate the fight between the two parties over the issue.

“If Democrats think they can run out the clock and win, they didn’t see the Super Bowl this year,” a senior Senate Republican aide said. “You can bet we’re going to highlight the stalling.”

Sen. Arlen Specter (Pa.), ranking Republican on the Judiciary Committee, asked Leahy in a recent letter to move on a number of the nominees. But if that doesn’t generate action, Republicans plan to take a more confrontational approach, such as denying a quorum during business committee meetings of the Judiciary Committee, aides said.

Bush has floated four names for the five open seats on the 4th Circuit. Last month, Duncan Getchell, a Richmond-based lawyer, withdrew from consideration after the Senate slow-walked his nomination due to criticism from his home-state senators, Republican John Warner and Democrat Jim Webb. The two complained that Bush brushed aside their suggestions to find a consensus nominee and tried to push through a nominee who had generated opposition from the left. Bush has not yet proposed a new nominee for that post.

Three other nominees are pending before the court: Robert Conrad, the chief judge of the Western District of North Carolina, who was nominated last July; attorney Steve Matthews of South Carolina, who was nominated in September and used to work in the Reagan Justice Department; and Rod Rosenstein, who was floated last November and currently serves as the U.S. attorney in Maryland.

Conrad and Matthews both have the support of their home-state Republican senators, but their background has sparked opposition from the left. Matthews sits on the board of the conservative Landmark Legal Foundation, which in 2007 nominated Rush Limbaugh for the Nobel Peace Prize. Conrad has generated opposition for some of his past writings, including a 1988 op-ed that called the anti-abortion group Planned Parenthood a “radical fringe group” and a 1991 article criticizing basketball star Magic Johnson for failing to promote abstinence and instead advocating safe sex as an effective means of HIV prevention.

Republicans say critics have cherry-picked issues that are not representative of the qualifications of the nominees.

Rosenstein’s background has not come under criticism from Maryland’s senators, Democrats Barbara Mikulski and Ben Cardin, but both have withheld support because he was not among the list of consensus nominees they asked Bush to choose.