Washington --

Conservative interest groups and Republican lawmakers want Justice Elena Kagan off the health care case. Liberals and Democrats in Congress say it's Justice Clarence Thomas who should sit it out.

Neither justice is budging - the right decision, according to many ethicists and legal experts.

None of the parties in the case has asked the justices to excuse themselves. But underlying the calls on both sides is their belief that the conservative Thomas is a sure vote to strike down President Obama's health care law and that the liberal Kagan is certain to uphold the main domestic achievement of the man who appointed her.

The stakes are high in the court's election-year review of a law aimed at extending coverage to more than 30 million people. Both sides have engaged in broad legal and political maneuvering for the most favorable conditions surrounding the court's consideration of the case.

Taking away just one vote potentially could tip the outcome on the nine-justice court.

Republican lawmakers recently have stepped up their effort against Kagan, complaining that the Justice Department has not fully revealed her involvement in planning the response to challenges to the law. Kagan was Obama's solicitor general, the administration's top Supreme Court lawyer, until he nominated her to the high court last year.

"The public has a right to know both the full extent of Justice Kagan's involvement with this legislation while she was solicitor general, as well as her previously stated views and opinions about the legislation while she was serving as solicitor general," the House Judiciary Committee chairman, Rep. Lamar Smith, R-Texas, said Tuesday in a letter to Attorney General Eric Holder.

Democrats have said Thomas has a conflict of interest stemming from the work of his wife, Virginia, with several groups that opposed the health care overhaul.

"From what we have already seen, the line between your impartiality and you and your wife's financial stake in the overturn of health care reform is blurred," 74 Democrats wrote Thomas in February.

The campaigns against the justices are partisan, suggesting to some legal experts that the complaints are less about perceived conflicts than the outcome of the health care case.

Looking at the claims made against Thomas and Kagan, University of Notre Dame law professor Richard Garnett said, "I don't think there's really a plausible case that either of these two justices should feel the need to recuse themselves."

Federal law requires any judge to sit out a case in which one of several conditions is met, including if "his impartiality might reasonably be questioned."

Another provision of the law that has triggered Kagan's decision to stay out of 28 cases since she joined the court concerns a judge who formerly served as a government lawyer. A judge should not participate if he or she served as counsel or adviser "concerning the proceeding or expressed an opinion concerning the merits of the particular case in controversy."

Kagan testified during her confirmation hearing in 2010 that she "attended at least one meeting where the existence of the (health care) litigation was briefly mentioned, but none where any substantive discussion of the litigation occurred." Kagan left the administration in August, about five months after the health care overhaul became law.

Some opponents of the law said e-mails released by the Justice Department under the Freedom of Information Act show Kagan had greater involvement in the administration's legal strategy than she acknowledged.

Each side has said public confidence in the court will be hurt by the targeted justice's participation in the health care case.