President Obama answers questions during a press conference following the 10-nation Association of Southeast Asian Nations summit in Rancho Mirage, Calif., on Feb. 16, 2016. (Reuters/Mike Blake

How does a president go about filling a vacancy on the Supreme Court? Here’s a primer on how the process works once a position opens up on the nation’s highest court.

  1. There’s already a list of potential nominees in place. The White House Counsel’s office maintains a list of potential nominees on hand, along with some basic information about them, long before an opening appears. The first step any White House undertakes is to update that list—which is what’s happening right now, even though the president spent the past few days doing fundraising and meeting with Southeast Asian leaders in California.
  1. An informal working group is assembled. Selecting and shepherding a nominee draws on several sections of the White House, including not just the counsel’s office but legislative affairs, the vice president’s office and the chief of staff. The attorney general is usually involved as well, and top congressional leaders often offer input as well. GOP strategist Ken Duberstein, who helped shepherd half a dozen Supreme Court nominees both as a White House staffer and as a pro-bono "sherpa" after he had left for the private sector, said in an interview that it is critical the administration reaches out to both parties on Capitol Hill. "There has to be some consultation, on both sides of the aisle, coming from the White House," Duberstein said.
  1. The president reviews dossiers on individual candidates. These files can include not only biographical information and some of the potential nominee’s most significant judicial opinions, but some of their non-judicial writings as well.
  1. Once the list is narrowed, candidates undergo interviews. All the finalists—a group that numbers half a dozen or less—are interviewed by the president before he settles on his selection.
Washington Post reporter Juliet Eilperin explains the difficulties ahead facing both Republicans and Democrats as they battle to fill the vacant Supreme Court seat left by the sudden passing of Associate Justice Antonin Scalia. (Dalton Bennett/The Washington Post)
  1. The president makes his choice. While this process can vary depending on who occupies the Oval Office, the selection of a Supreme Court nominee is a personal one—especially in the case of Obama. “When he makes the final, final decision, he’s in a room by himself,” said Ron Klain, who helped spearhead the confirmation campaigns for Justices Sonia Sotomayor and Elena Kagan during the president’s first term. “I don’t think it’s possible to overstate how deeply and personally the president takes this decision. This is something he really does himself.” President George W. Bush consulted closely with other aides, though his personal preferences were also shown in his picks. He initially selected his own White House counsel, Harriet Miers, only to back down in the fact of bipartisan opposition, and nominated Samuel A. Alito instead. And for Bush and Vice President Richard B. Cheney, according to Cheney's former general counsel Shannen Coffin, a strict reading of the Constitution was paramount. "They were looking for respect for the rule of law and the Constitution," Coffin said, adding, "The Constitution as written, not the constitution as dreamed up by five people wearing black robes."
  1. The campaign for confirmation begins. Presidents have deployed a couple different approaches to this task in recent years. Presidents George H.W. Bush, Bill Clinton and George W. Bush all enlisted outside lawyers to help shepherd their nominees through the Senate: Duberstein helped both David Souter and Clarence Thomas when they encountered Democratic resistance, Michael Berman took up Ruth Bader Ginsburg’s cause and Ed Gillespie worked on Alito's nomination. In his book, Gillespie said he took leave from his lobbying firm to work as a “special government employee… full time managing message, preparing for Senate hearings, working with outside groups and being a link to senators on the Judiciary Committee.“ A batch of Clinton-era memos released in 2014 show that White House officials worried about how Ginsburg would fare on the Hill, given the fact that conversations with her frequently involve stretches of silence. “She pauses, takes deep breaths, and then answers,” details one unsigned memo, though the anonymous author praises the nominee in the same document that she “has incredible powers of recollection.” For his past two nominees, Obama has relied strictly on staff to handle the confirmation process, but no decision has been made yet on this nomination.Republicans are poised to be skeptical no matter what, especially since they feel a number of justices--including Kagan and John G. Roberts Jr.--have proven less moderate than they appeared during their confirmation process. "Everyone realizes we need to focus on actions, rather than words," said Carrie Severino, chief counsel and policy director for the conservative Judicial Crisis Network.
  1. In this case, a rough ride is sure to ensue. This would be the first time a president has sent a Supreme Court nomination over to the Senate controlled by the other party in a quarter century, since George H.W. Bush nominated Thomas in 1991. All the other nominations since then – Ginsburg, Stephen G. Breyer, John G. Roberts Jr., Miers, Alito, Sotomayor, Kagan – involved either Democratic presidents and a Democratic-controlled Senate or Republican presidents facing a GOP-controlled Senate. And while past is often prologue, this nomination faces such a different set of odds compared to ones in recent memory, it is difficult to predict how the White House will proceed. On other occasions, a president could take comfort in the fact that even if one nomination died on Capitol Hill, he could offer up another in its place. In this instance, President Obama has just one last chance to seat someone on the Supreme Court—and even that shot faces very long odds.