WASHINGTON – Judge Samuel Alito gained the American Bar Association’s highest rating for a Supreme Court nominee, giving him a boost before next week’s Senate confirmation hearings.

Interest groups will now try to help or hinder Judge Alito’s chances by spending hundreds of thousands of dollars on television, radio, and Internet ads nationwide and in the states of key senators, before and during the Senate Judiciary Committee’s hearings.

This is the second time the ABA, the nation’s largest lawyers’ organization, has rated Judge Alito, who was nominated by President Bush on October 31 as the replacement for retiring Justice Sandra Day O’Connor.

The “well qualified” rating – the highest – is the same one that Judge Alito earned in 1990 when Mr. Bush’s father, George H.W. Bush, nominated him to the 3rd U.S. Circuit Court of Appeals.

Embracing the latest rating, White House spokesman Scott McClellan said, “Leading Senate Democrats have said in the past that the ABA is the – quote – gold standard for evaluating judicial nominees.”

Democrats contend Judge Alito is too conservative and could undermine abortion rights. They are expected to be Judge Alito’s toughest questioners at the hearings that begin Monday.

“The ABA ratings do not take into account whether a judge’s judicial philosophy and views are in or out of the broad mainstream,” Senator Schumer said. “That is the $64,000 question with Judge Alito, and we will have to wait for the hearings to get a better answer.”

For more than 50 years, the ABA has evaluated judicial nominees’ credentials, though the organization has no official standing in the process. In 2001, Mr. Bush ended the ABA’s preferential role in vetting prospective nominees and refused to give the group advance word on names under consideration.

The ABA’s Standing Committee on Federal Judiciary came up with the rating after confidential interviews with hundreds of Judge Alito’s colleagues and a review of his writings. Their options were well-qualified, qualified, and not qualified.

“The committee is of the unanimous opinion that Judge Samuel A. Alito Jr. is well-qualified,” the chairman of the ABA panel, Stephen Tober, said.

One member of the committee abstained from voting, Mr. Tober said. He did not explain why that person did not vote. The group will testify during Judge Alito’s confirmation hearing about how it arrived at the rating.

The rating will not stop some people from attacking Judge Alito, said Senator Cornyn, a Republican of Texas and a member of the Senate Judiciary Committee. “Unfortunately, the hard left groups decided long before these ratings were announced that they would oppose his nomination,” Mr. Cornyn said.

Interest groups have spent much less on TV commercials on Judge Alito’s nomination than they did when Mr. Bush elevated John Roberts to the high court, Deborah Goldberg, director of the Democracy Program at the Brennan Center for Justice, said.

Ms. Goldberg estimated that such groups spent $1.3 million during the confirmation process for Judge Roberts, now the chief justice. About $325,000 was spent on Harriet Miers’s nomination before Mr. Bush’s aide withdrew from consideration, and, before this week, about $650,000 on Judge Alito’s nomination, Ms. Goldberg said.

At least two liberal groups – MoveOn.org Political Action and IndependentCourt.org – plan to take to the airwaves this week to try to build public momentum against Judge Alito. MoveOn.org is spending $150,000 for an ad airing nationwide on CNN, and IndependentCourt.org, a coalition of dozens of liberal interest groups, is beginning a national TV ad.