President-elect Obama will enter office with an immediate opportunity to begin shaping the federal courts by filling four dozen openings on trial and appeals courts.

Federal judges, with lifetime appointments, can be a president’s most enduring legacy. President Bush receives uniformly high marks from Republicans, even those who criticized him on other issues, for his selection of Chief Justice John Roberts and Justice Samuel Alito.

Public attention typically is focused on the Supreme Court, where five justices are older than 70. Speculation about a possible opening centers on 88-year-old Justice John Paul Stevens, but any retirement is unlikely before the summer, if then.

By contrast, 14 seats are open on appeals courts or will be by the end of January. Democratic appointees are a majority on only one of the 13 federal appeals courts, the San Francisco-based 9th U.S. Circuit Court of Appeals.

These are the courts that as a practical matter have the final say on everyday issues that affect millions of people because the Supreme Court accepts less than 2 percent of the cases appealed to the justices.

“Most of the action is in the lower courts, from labor and employment law to civil rights to punitive damages to affirmative action and how the death penalty is administered,” said Ilya Shapiro, senior fellow in constitutional studies at the libertarian Cato Institute in Washington.

The traditionally conservative 4th U.S. Circuit Court of Appeals, based in Richmond, Va., is the first court on which Obama can change the balance of power quickly. It has four openings and is divided now between five judges appointed by Republican presidents and five named by Democrat Bill Clinton.

Covering Maryland, the Carolinas and Virginia, the 4th Circuit hears a large share of national security and intelligence cases because Virginia is the home of the Pentagon and the Central Intelligence Agency.

Shapiro estimates that within four years, Obama can name enough judges to give Democrats majorities on nine of the 13 appeals courts.

Nan Aron, president of the liberal Alliance for Justice, has complained that Bush appointees have been more likely to rule in favor of executive authority, businesses in their disputes with workers and consumers, and limiting access to the courts.

Judges appointed by Obama can be expected to side more often with “workers, consumers, homeowners, women and people of color who were discriminated against,” Aron said.

With Democrats holding a solid majority in the Senate, at least for the next two years, Obama is not likely to have trouble getting his appointees confirmed. Bush and Clinton both struggled with the Senate when it was under the control of the opposition party for parts of their presidencies.

Some of the openings have existed for years, a result of Senate rules that give individual senators wide power to block nominees. In other cases, Bush has moved slowly to fill openings or Democrats have objected to the conservative backgrounds of his choices.

Among the appeals court seats to be filled are those vacated by Roberts in 2005 and Alito in 2006 when they were elevated to the Supreme Court.

Even when Clinton had a Democratic Senate majority in his first two years as president, he was slow to nominate judges, although an unexpected early retirement announcement by Supreme Court Justice Byron White partly accounted for the delay in moving other nominations.

The incoming Obama administration is unlikely to repeat that mistake, in part because of the experience of high-ranking officials beginning with Vice President-elect Joe Biden, a senator from Delaware who served 32 years on the Senate Judiciary Committee.

Biden was chairman of the committee, which reviews judicial appointments, during the explosive debates over Supreme Court nominees Robert Bork in 1987 and Clarence Thomas in 1991. He led the committee for eight years and was its top Democrat for eight more during Democratic and Republican presidencies.

“This presidential team has more experience and expertise on these issues than any in history,” said Doug Kendall, president of the liberal Constitutional Accountability Center. “You’d expect this is something they will get right.”

Conservatives tried to make a campaign issue of the potential for Democrats to remake the federal judiciary under Obama after Republican administrations since 1981 installed many young, right-leaning judges.

Even on the Supreme Court, where the justices often divide 5-4 on ideologically charged issues, seven justices were appointed by Republicans.

The court’s two oldest justices, Stevens and Ruth Bader Ginsburg, 75, are considered the most likely to retire soonest, yet both have hired law clerks for the next court term that begins in 11 months — a signal they might be planning to stay.

Curt Levey, executive director of the conservative Committee for Justice, is worried about the prospect of two Obama terms. He has said that there is a 75 percent chance that Obama eventually will have the chance to replace not only several liberal justices, but also the older conservative justices as well and create a liberal majority.

He pointed out that in this “unsettling scenario” Justices Antonin Scalia and Anthony Kennedy both would turn 80 in the final year of a hypothetical second Obama term and one or the other is likely to retire by then.