In bitingly partisan exchanges yesterday, lawmakers plunged into the dispute over Karl Rove's hand in leaking a covert CIA operative's identity, as the Senate rejected a bid to strip the White House aide of his security clearance.

A day of dueling news conferences ended with a Senate debate that turned unusually personal. It began when Democratic leaders proposed an amendment, aimed at Rove, to deny access to classified information to any federal employee who discloses a covert CIA agent's identity.

Republican leaders retaliated with a measure designed to strip the security clearances of the chamber's top two Democrats. Even as he urged support for his amendment, Majority Leader Bill Frist (R-Tenn.) acknowledged the blatantly political tone of the debate. "This is a sad and a disappointing afternoon here in the United States Senate," he said.

Frist's amendment failed, 64 to 33, when 20 Republicans joined all present Democrats in voting against it. The Senate then rejected the Democrats' measure aimed at Rove, by a 53-to-44 vote along party lines. Both items were offered as amendments to a homeland security appropriations bill.

Rove, President Bush's deputy chief of staff, accompanied the president on a trip to Indianapolis -- both men walking together from the White House to the Marine One helicopter on the South Lawn. Bush usually walks alone to the helicopter, and their public stroll was widely perceived as a presidential show of support.

Through his attorney, Rove in recent days has acknowledged discussing CIA official Valerie Plame -- though not by name -- with a Time magazine reporter shortly before columnist Robert D. Novak named her in a July 2003 column, citing two senior administration officials as his sources. Plame's husband, former ambassador Joseph C. Wilson IV, had written that the Bush administration manipulated intelligence about Iraq's pursuit of nuclear weapons material to justify the invasion there and the ouster of Saddam Hussein.

Democrats say the White House unmasked Plame in an effort to undermine Wilson's allegations. As part of its case for going to war in 2003, the administration cited evidence that Iraq may be trying to obtain uranium in Niger. Wilson said his own 2002 trip showed there was no evidence for such a claim. But administration officials told reporters that Wilson's Niger trip deserved little credibility, since he was dispatched at the recommendation of his wife at the CIA. A special counsel is investigating, and Rove is among several senior White House officials who have spoken to a grand jury.

Sen. Charles E. Schumer (D-N.Y.) hosted Wilson at a Capitol news conference yesterday in which both men criticized Rove and defended Wilson's allegations of manipulated Iraq intelligence. "I made my bones confronting Saddam Hussein and securing the release of over 2,000 Americans in hiding in Kuwait," Wilson said. "Karl Rove made his bones doing political dirty tricks." Several House Democrats also criticized Rove.

Senate Republicans responded with their own news conference. "I have seen nothing so far that would indicate that there was any law broken by Karl Rove," Sen. Kay Bailey Hutchison (Tex.) said. Sen. Christopher S. Bond (Mo.) said: "Joe Wilson's attacks were a political sham. They were then, and they still are today."

On the Senate floor, Minority Leader Harry M. Reid (D-Nev.) offered the measure targeting Rove's security clearance, and Frist offered his aimed at Reid and Democratic Whip Richard J. Durbin (Ill.). Frist's amendment would have denied clearance to any senator who refers to a classified FBI report on the floor, a shot at Reid's May 12 reference to a report on a Bush judicial nominee. It also would have stripped access to classified information to an officeholder making a statement that is "based on an FBI agent's comments which is used as propaganda by terrorist organizations." That was aimed at Durbin's comments last month comparing the treatment of detainees at the U.S. military prison at Guantanamo Bay, Cuba, to techniques used by the Nazis and the Khmer Rouge.

Reid called Frist's amendment "about as juvenile and as mudslinging as I have seen."

A dismayed Sen. Susan Collins (R-Maine) vowed to vote against both measures and chastised her colleagues for veering from the homeland security funding issue. "This is exactly why the American public holds Congress is such low esteem," she said in a brief floor speech.

On Frist's amendment, several Republicans did not vote nay until it was clear the measure would fail. Virginia and Maryland senators voted against the Frist amendment except for Barbara A. Mikulski (D-Md.), who was absent.

President Bush's walk with Karl Rove, center, from the White House to the Marine One helicopter was viewed as Bush's show of support for his deputy chief of staff. Accompanying them was domestic policy assistant Claude Allen. Rove accompanied the president on a trip to Indianapolis.