WASHINGTON -- In his search for a replacement for the late conservative Supreme Court Justice Antonin Scalia, President Barack Obama is focusing on a small group of appellate court judges with largely traditional credentials and a history of bipartisan backing.

The choices suggest the White House plans to challenge the Republican Senate to block a nominee who otherwise might face a relatively easy confirmation if the fight weren't playing out in an election year.

Many expect Obama to announce his pick next week. The court is currently split 4-4 between liberal and conservative justices.

Obama said Thursday he's holding out hope that "cooler heads will prevail" and Republicans will back down from their plan to block his nominee.

He said he's looking for a candidate with "humility," who doesn't make policy from the bench, and someone who recognizes the role judges play in protecting minorities.

Obama's top tier of candidates include Judge Sri Srinivasan of U.S. Court of Appeals for the District of Columbia Circuit, Merrick Garland, chief judge on same court, and Judge Paul Watford of the 9th U.S. Circuit Court of Appeals, according to a source familiar with the selection process. Ketanji Brown Jackson, a D.C. district court judge, is also under consideration, although a less likely option, said the source, who asked not to be identified because the person was not authorized to publicly discuss private White House deliberations.

The judges' inclusion on the short list was first reported by National Public Radio, which also named Judge Jane Kelly of the 8th Circuit Court of Appeals as a finalist being interviewed by the president.

The emerging list, which the White House says is not final, seems in line both with Obama's personal and political aims. As he has in his past two nominations, Obama appears drawn to candidates with traditional resumes: Supreme Court clerkships, prestigious posts in government and experience at major law firms.

The list also shows the president considering whether to add racial or gender diversity to the court. Srinivasan, 49, would be the first Indian-American on the court, while Watford, 48, would be the third African-American to hold a seat. Brown Jackson, 45, would be the first African-American woman.

But the push to make history appears to be just part of a complex mix of calculations. Facing Republicans vowing to block any nominee, the White House has stressed that the nominee will have "impeccable" credentials, suggesting the choice will have a record so strong it will shame Republican senators into backing down.

Obama's consideration of Garland appears to fit into that approach. Garland, a white, 63-year-old with an Ivy League, East Coast background, would not add diversity to the court. But with a reputation as a judicial moderate and with broad respect in Washington, the choice of Garland could put maximum pressure on some Republican senators.

Both Srinivasan and Watford come with some bipartisan endorsement. Srinivasan was unanimously confirmed to the bench in 2013. Watford's confirmation vote was a more partisan 61-34 split.

As Obama appointments, neither comes with long records on the bench, leaving their judicial philosophies somewhat ambiguous.

The president appears to have ruled out naming a politician or administration official, despite briefly considering Attorney General Loretta Lynch. On the short list, only Kelly, a former public defender in Iowa, did not follow the traditional ladder to the highest court.

Over half of Americans in a February Pew Research Center poll backed Senate hearings and a vote on a nominee, while an NBC News-Wall Street Journal survey early this month found that more disapprove than approve of Republicans ignoring an Obama nominee by about 2-1.

Associated Press writer Alan Fram in Washington contributed