A senior Republican senator says he's troubled by U.S. President Barack Obama's criteria in favoring judges that show "empathy" to petitioners.

Sen. Jeff Sessions, R-Ala., the top Republican on the Senate committee reviewing federal appeals court Judge Sonia Sotomayor's nomination to the U.S. Supreme Court, told USA Today that Obama is moving the federal courts "far to the left" and is sacrificing the principle of impartiality when he looks for judges who can empathize with the life experiences of low-income or minority people.

"I'm troubled, I have to say, by President Obama's philosophy of judging," Sessions said. "When he talks about wanting a judge to show empathy, that's very troubling to me."

Speaking of Sotomayor, Sessions told the newspaper, "She seems to be willing to accept that a judge's rulings may be influenced by the judge's personal backgrounds or feelings, which is sort of what President Obama has said," alleging that three other federal court nominations carry the same taint.

University of Pittsburgh law professor Arthur Hellman, however, disagreed, telling USA Today the differences between the nominees -- David Hamilton, Andre Davis and Gerard Lynch -- are greater than their similarities.

Sotomayor's confirmation hearing is set to begin July 13.