Parties air impassioned views on Kagan

“She’ll base her approach to deciding cases on the law and the Constitution, not on politics, not on an ideological agenda,’’ said Senator Patrick Leahy, Democrat of Vermont, the chairman of the Judiciary Committee. He said today’s Supreme Court is populated by “activist conservative members’’ who substitute their own judgment for that of lawmakers.

Republicans countered that Kagan is an inexperienced, disingenuous nominee who would abuse her post by bending the law to suit a liberal agenda.

“I don’t think it’s a secret. I think this is pretty well known that this is not a judge committed to restraint, [or] objectivity,’’ said Senator Jeff Sessions of Alabama, the top Republican on the Judiciary Committee. Her past actions and testimony indicate she would be “an activist, liberal, progressive, politically minded judge who will not be happy simply to decide cases but will seek to advance her causes under the guise of judging.’’

Even her harshest critics acknowledged there was no doubt about the debate’s outcome and the vote expected tomorrow, with the support of all Democrats and five GOP senators.

“I hope I’m wrong about soon-to-be Justice Kagan,’’ said Senator Orrin Hatch, a Utah Republican.

In line to become the fourth woman ever to sit on the court, Kagan is not expected to alter its ideological balance in succeeding retired Justice John Paul Stevens — himself a leader of the Supreme Court’s liberal wing.

Even as senators spoke passionately on the Senate floor about granting Kagan a lifetime position on the nation’s highest court, the debate was drawing remarkably little attention on Capitol Hill, where lawmakers preparing for midterm elections are preoccupied by bad economic news and the aftermath of the Gulf of Mexico oil spill.

Kagan earned barely a mention at Democrats’ and Republicans’ news conferences yesterday — and then only as the last on a list of things left to do before senators depart for a monthlong vacation.

Still, the discussion on the nominee was infused with politics, coming just months before midterm congressional elections.

A conservative group heaped criticism on the Republican senators who have announced plans to join Democrats in supporting Kagan, singling out Senator Lindsey Graham of South Carolina, the first defector, for special contempt.

The Traditional Values Coalition also blasted Kagan’s other GOP supporters, Senators Susan Collins and Olympia Snowe of Maine, retiring Senator Judd Gregg of New Hampshire, and Senator Richard Lugar of Indiana.