By Chantal Valery (AFP)

WASHINGTON — As US President Barack Obama dives into his second term and looks to build his legacy, his appointments of federal judges, especially to the Supreme Court, appear certain to make a lasting impact.

Over the next four years, the Democratic president will have the opportunity to pull a largely conservative federal bench towards the left, with about 100 vacancies to fill and a Supreme Court that could have up to three openings.

“It is typically in the second term that presidents tend to handle the legacy issues,” said Doug Kendall, president of the Constitutional Accountability Center, a Washington-based think tank.

“He has to exercise his constitutional right and authority,” Kendall told a recent conference, urging Obama to appoint “moderates” to respond to the “very radical vision of the Constitution” espoused by some ultra-conservative judges.

Unlike in individual states where judges are elected by popular vote, the president names judges to the bench in the US federal court system — comprised of 89 trial courts, 13 appellate courts and the Supreme Court.

The US Senate must confirm all judicial nominees.

Currently, most of the 179 appeals judges and 678 trial judges were named by Republican presidents over the last three decades, and the highest courts lean towards the right.

“President Obama really has to be the commander-in-chief in terms of diversifying” the courts, said Caroline Fredrickson, president of the progressive American Constitution Society for Law and Policy.

The US needs “to have a court system that is actually fair and balanced” both politically and socially, she said.

Frederickson hailed Obama for increasing the number of women, homosexuals and minorities on the federal bench — including the two women he put on the Supreme Court.

But she said the November 6 election, in which Obama handily defeated Republican rival Mitt Romney, served as a “wake-up call” on women’s and family issues, and a win over “shocking words on rape and abortion” from the right.

During the campaign, Republican Senate candidates Todd Akin from Missouri and Richard Mourdock from Indiana sparked national outrage with their comments about rape and abortion. Both candidates lost their respective races.

The judiciary is meant to be non-partisan, noted Andrew Blotky, director of legal policy issues at the left-leaning Center for American Progress, saying “judges shouldn’t be policymakers.”

But whether it’s health care reform, voting rights or affirmative action, just a few of the issues taken up by the Supreme Court in recent months, Blotky said “courts play a significant and long-term role on American life.”

Obama’s Republican predecessor George W. Bush “flooded the zone” with like-minded judges, said Ian Millhiser, a constitutional policy analyst also with the Center for American Progress.

Bush named 12 appeals court judges and two Supreme Court judges, including the current chief justice John Roberts.

Now that he has the chance, “Obama has to flood the zone” to restore judicial equilibrium, Millhiser said.

After naming Sonia Sotomayor and Elena Kagan to the nine-justice Supreme Court, Obama may have the opportunity to replace as many as three more who will be over the age of 80 by 2015.

Speculation has focused on Ruth Bader Ginsburg, 79, who suffers from cancer.

But his impact could be felt across the system, as the vacancies on lower courts have mounted over the past four years, in part because Obama struggled to get his appointees confirmed by the Senate.

Although the Democratic Party holds a majority in the chamber, Republicans can use legislative maneuvers to block nominations or at least make the process more cumbersome.

John Podesta, the chair of the Center for American Progress and a former White House chief of staff under Bill Clinton, said reforms to the process of confirming judges in the Senate are necessary.

Millhiser noted that if Obama does not respond to the challenge at hand, “we will have a future president in 2016 who will.”