President Bush named his trusted White House counsel Harriet E. Miers, a Texas native with no experience as a judge, to replace retiring Supreme Court Justice Sandra Day O'Connor, sparking an outcry among conservative activists who had hoped for a hard-line jurist with clear ideological positions.

Bush called Miers, a prominent commercial litigator in Dallas before she followed him to Washington, a legal "pioneer" who has worked to topple gender barriers. He said she would be an "outstanding addition" to the court.

"She has devoted her life to the rule of law and the cause of justice," Bush said in an early morning announcement yesterday from the Oval Office.

In choosing Miers, a blank-slate nominee best known for her closeness to Bush, the president confounded critics and allies who had expected him to choose a judge with solid conservative credentials who would provoke an explosive Senate fight over the future of the court.

Instead, senators and some interest groups on both sides of the political spectrum who had geared up for a fight reacted cautiously to the selection of Miers, 60, whose slim legal paper trail leaves open the question of whether she would follow O'Connor as a swing vote on the court or steer it decisively to the right.

"It is the responsibility of every generation to be true to the founders' vision of the proper role of the courts in our society," Miers said in her appearance with Bush, before making the trek up Pennsylvania Avenue to meet senators charged with considering her nomination.

"If confirmed, I recognize that I will have a tremendous responsibility to keep our judicial system strong, and to help ensure that the courts meet their obligations to strictly apply the laws and the Constitution."

There is evidence that Miers agrees with Bush on key questions, such as abortion. When Miers served as president of the State Bar of Texas from 1992 to 1993, she was a leader in the group's unsuccessful effort to get the American Bar Association to reverse its stance in favor of abortion rights.

Miers is seen as a power player in the Bush White House, where she has been a fierce protector of Bush and a key point-person on important issues, including a strategy for confirming his judicial nominees and the search process for filling both Supreme Court vacancies.

Bush first met with Miers about tapping her for the court Sept. 21, and he discussed the idea with her twice more over the past two weeks before officially offering her the job Sunday night, over dinner with his wife, Laura, at the White House.

Republican leaders praised Bush's choice, noting Miers' reputation as a tough and effective litigator, including a resume boasting several firsts: She was the first woman hired by a prestigious Texas law firm and first female president of the Dallas Bar Association and the State Bar of Texas.

Miers "is a woman who understands judicial restraint, a woman who has been a pioneer in Texas in terms of the legal profession," said Sen. Bill Frist of Tennessee, the majority leader. "Her experience, both in private practice and her experience as counsel to the president, will serve her well."

But some conservatives were conspicuous in their silence about the nomination, their offices saying privately that they would have no comment.

"I intend to carefully review the nominee's credentials and assess her qualifications and commitment to the rule of law," Sen. Rick Santorum of Pennsylvania said in a statement.

Democrats said they, too, would demand to know more about Miers before they decide whether she would be a good justice. But some senior members praised Bush's pick, signaling the party won't seek to block her through a filibuster.

The top Democrat, Sen. Harry Reid of Nevada, warmly endorsed Miers. "I have to say without any qualification that I'm very happy that we have someone like her," Reid said as he appeared, smiling, in the Capitol with Miers. Her lack of experience as a judge is "a plus, not a minus," he said.

Reid brushed aside questions about her scant paper trail, saying, "I just understand the broad outline of this woman. And the broad outline looks really good to me."

Sen. Barbara A. Mikulski, a Maryland Democrat and the dean of Senate women, said she was pleased that Bush had tapped a woman to replace O'Connor, adding that confirmation hearings would "play a highly determinative role" in her ultimate decision about Miers' qualifications.

She spoke admiringly of Miers' biography, which Mikulski said shows she is "tough," "scrappy," and "obviously a woman of backbone."