Bringing in the tea party movement - known for its high-energy rallies and protests calling for small government, lower taxes and less spending - would be a coup for conservatives, who were not able to stop the confirmation of Sonia Sotomayor last year.
This time, "you may have a whole new group of activists involved," said Tom Fitton of the conservative group Judicial Watch.
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The White House revealed Monday that Obama's candidates for the Supreme Court include a new name, federal appeals court judge Sidney Thomas of Montana, and at least six who were contenders when Obama chose Sotomayor as his first high-court nominee.
In the mix are former Georgia Chief Justice Leah Ward Sears, federal appeals court judges Diane Wood and Merrick Garland, Solicitor General Elena Kagan, Michigan Gov. Jennifer Granholm and Homeland Security Secretary Janet Napolitano. Those names have been confirmed to The Associated Press by the White House.
Not under consideration to replace retiring Justice John Paul Stevens is Hillary Rodham Clinton. White House press secretary Robert Gibbs said Obama "is going to keep her as his secretary of state."
Conservative groups like Judicial Watch and the Committee for Justice are already gearing up for what could be a summertime fight with the White House and Senate Democrats over Obama's pick.
Beyond their fiscally conservative principles, the ideology of the people involved in the tea party movement tends to vary dramatically. So far, tea party activists "haven't been interested in politics," Fitton said.
Curt Levey of the conservative Committee for Justice said he has been in contact with some tea party leaders trying to explain to them how an Obama judicial nomination affects their cause.
"Are we going to have big or small government? Should the Supreme Court have unlimited power?" he said.
And the health care overhaul? "That's going to end up in front of the Supreme Court, and if you care whether that bill survives or not, you better care about the Supreme Court," Levey said.
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Thomas, 56, of Billings, Mont., sits on the 9th U.S. Circuit Court of Appeals, the largest of the nation's appellate courts. It is also considered the most liberal of the nation's appellate courts.
Timothy Bechtold, chairman of the Montana Bar Association's federal practice section, said he wouldn't call Thomas' opinions "progressive or liberal or anything that could have a consistent tag line."
"I think that Judge Thomas is judge whose opinions tend to take the course necessary to follow the laws as the facts present them in a case," Bechtold said.
Thomas was nominated to the federal bench in July 1995 by President Bill Clinton and confirmed by the Senate in January 1996 with no controversy in a voice vote.
He comes from Western roots. He was born in Bozeman, Mont., and has a bachelor's degree from Montana State University and a law degree from the University of Montana. He worked in private practice in Billings and was an adjunct community college law professor there for years before becoming a federal judge.
"He doesn't carry a liberal nor a conservative bias like some judges do. He shoots straight down the middle," said Clifford Edwards, who has worked as a lawyer in Billings, Mont., for 36 years.
The background of others under Obama's review:
Wood, an appeals court judge in Chicago, has worked at the State Department, the Justice Department and in private practice. Like Obama, she taught at the University of Chicago Law School.
Kagan stepped down as dean of Harvard Law School to become the nation's first female solicitor general. Like Obama, she has her law degree from Harvard and taught at the University of Chicago Law School.
Granholm, the Michigan governor, is a former federal prosecutor and Michigan attorney general.
Napolitano, the homeland security chief, is a former Arizona governor and a former federal prosecutor.
Garland, of the federal appeals court in Washington, is a former high-ranking Justice Department official.
Sears, the first black woman to serve as the chief justice of the Georgia Supreme Court, is now in private practice after a long career on the bench.