Members of the Senate Judiciary Committee Tuesday begin questioning Judge John Roberts, President Bush's nominee to be chief justice of the U.S. Supreme Court.   Abortion is expected to be a key issue in the questioning.

Senate Democrats, noting that Supreme Court justices are the final arbiters on issues that can affect all aspects of Americans' daily lives, are vowing to press Judge Roberts to explain his views on a range of controversial issues, including abortion.

Democrats are concerned by a legal brief the nominee helped write while serving at the Justice Department in President Bush's father's administration.  The brief said the 1973 landmark Supreme Court case known as "Roe versus Wade" establishing a constitutional right to abortion was "wrongfully decided and should be overruled".

On the first day of confirmation hearings Monday, Senator Dianne Feinstein - a California Democrat and the only woman on the committee - underscored her concern to Judge Roberts:

"It would be very difficult, and I said this to you privately and I have said it publicly, for me to vote to confirm someone whom I knew would overturn Roe v. Wade," Senator Feinstein says.

Republicans have said the brief simply reflected the official legal position of the administration at the time. Two years ago, during confirmation hearings for his current position as appeals court judge, Judge Roberts said he viewed the decision finding a constitutional right to abortion as "settled law."

But at Monday's hearing, Senator Sam Brownback, a Kansas Republican and staunch abortion foe, said he saw "Roe versus Wade" and another 1973 Supreme Court case known as "Doe versus Bolton," which struck down restrictions on abortion, as anything but settled law:

"Perhaps the Supreme Court's most notorious exercise of raw political power came in Roe versus Wade and Doe v. Bolton, two 1973 cases based on false statements which invented a constitutional right to abortion," Senator Brownback says.

Some Republicans are urging Judge Roberts not to answer questions that could force him to prejudge cases that may come before the high court.

Committee Chairman Arlen Specter, a Pennsylvania Republican, says that is up to the nominee: 

"Senators have the right to ask whatever questions they choose, and you Judge Roberts have the prerogative to answer the questions as you see fit, or not to answer them as you see fit," Senator Specter says.

For his part, Judge Roberts says he does not have an agenda for the Supreme Court:

"If I am confirmed, I will be vigilant to protect the independence and the integrity of the Supreme Court, and I will work to ensure that it upholds the rule of law, and safeguards those liberties that make this land one of endless possibilities for all Americans," Judge Roberts says.

The hearings are expected to last much of the week.  Republican leaders hope Judge Roberts can be confirmed by the full Senate before the Supreme Court opens its new term October third.