ANTONIN SCALIA’s death on February 13th emptied a seat at America’s Supreme Court for the first time since 2010. Six years ago, a mere six weeks following the retirement of John Paul Stevens after 35 years on the bench, Elena Kagan was sworn in as the nation’s 112th justice. A longer and more contentious battle awaits the 113th. Moments after news broke of Mr Scalia’s death, political jockeying began over the issue of appointing his successor. Republicans in the Senate and on the campaign trail insisted that the seat should remain vacant until the next president enters the White House in 2017. Barack Obama rejected this proposition hours later, saying he would fulfil his “constitutional responsibilities to nominate a successor in due time”. With nearly a year remaining in his second term, Mr Obama added, “there will be plenty of time for me to do so, and for the Senate to fulfil its responsibility to give that person a fair hearing and a timely vote”. America’s constitution says presidents “shall nominate...judges of the supreme court”, along with “ambassadors, other public ministers and consuls...and all other officers of the United States”. But to “appoint” individuals to any of these offices, “the advice and consent of the Senate”, the upper house of America’s parliament, is required. The dual process reflects the framers’ strategy of curtailing the power of individual branches of the federal government through checks and balances: the president proposes, the Senate disposes. In practice, this means that before deciding their fate, senators invite potential justices to their chamber for weeks of confirmation hearings where they are quizzed about their experience and judicial philosophy. The 20-member Judiciary Committee, currently led by Charles Grassley, a Republican from Iowa, vets the nominee and holds a vote. Then, barring an extension of debate via a filibuster (which the 46 Democratic senators would find it near-impossible to fight, as they would need the help of at least 14 Republicans to reach the 60 votes required to invoke “cloture”), the full Senate votes. It takes 51 votes to confirm.

Historically, presidents have had a rather easy time getting their favoured candidates onto the highest court. Of the 160 names that have been sent to the Senate since 1789, 7.5% (12 nominees) were formally rejected while about 5% (9) were not acted upon. Another 7.5% had their names withdrawn before the Senate voted. But since 1987, when Ronald Reagan’s nomination of Robert Bork, an outspoken conservative, received a chilly reception from Senate Democrats (he was defeated by a vote of 58-42), the process has become much more heated. In 1991, Clarence Thomas, dogged by allegations of sexual harassment and questions about his stance on abortion, squeaked into his seat with a 52-48 majority, one of the the narrowest margins ever. Bill Clinton nominees Ruth Bader Ginsburg (96-3) and Stephen Breyer (87-9) commanded warmer majorities, while subsequent confirmations have been more vexed: George W. Bush nominees Chief Justice John Roberts (78-22) and Samuel Alito (58-42); and Sonia Sotomayor (68-31) and Elena Kagan (63-37), both appointed by Mr Obama.

Feverish but highly secretive discussions are underway in the White House to narrow a long list of possible nominees. Mr Obama will soon conduct covert interviews with a handful of candidates. With the distinct possibility that Republicans will refuse to move on anyone he nominates, Mr Obama’s choice will reflect both his jurisprudential priorities and his calculation of how to inflict the most political damage on the GOP should the party follow through on its promise to leave Mr Scalia’s seat vacant until the next administration is seated. By nominating a centrist with a record of bipartisan support—someone like Sri Srinivasan, confirmed by a 97-0 vote to the federal appeals court for the District of Columbia in 2013—Mr Obama could embarrass Republicans by forcing them into the role of hyper-politicised obstructionists. He could also give the Democratic nominee for president a leg up in this summer’s campaign.