The full US Senate has begun a final debate on the nomination of Samuel Alito to serve on the US Supreme Court.
Democrats say Judge Alito would make the court more conservative
Senate majority leader Bill Frist said Mr Alito was "exceptionally qualified" at the start of debate which looked set to unfold along party lines.
The Republican-led Senate is expected to confirm the conservative judge who was nominated by President Bush.
Democrats argue that Mr Alito would swing the influential court too far to the right, affecting US life for years.
The Supreme Court has the power to strike down laws passed by Congress and to rule on key issues like abortion and gay rights.
Mr Alito would replace Justice Sandra Day O'Connor, who often held the swing vote on key issues.
Opening the debate, Mr Frist told senators: "I support Judge Alito because he has a record that demonstrates a respect for judicial restraint and aversion to political agendas on the bench and a commitment to the rule of law and the Constitution.
"There is no question that Judge Alito is well-qualified."
Democratic Senator Edward Kennedy, meanwhile, said the judge's views on the limits of executive power would break the Supreme Court's traditional check on the powers of the president.
"If confirmed, Judge Alito would have enormous impact on our basic rights and our liberties for decades to come," he said.
Republicans want to get Mr Alito on the Supreme Court before Mr Bush's State of the Union speech on 31 January, but they have not yet reached an agreement with Democrats on when a final vote will occur.
Debate was expected to last a week.
As of late Tuesday, the federal appeals court judge was reported to have enough vote commitments for confirmation with a simple majority in the 100-member Senate, in which Republicans have a 55-45 seat majority.
The justices of the Supreme Court are appointed until they die, resign or are impeached.
Mr Bush's earlier choice for the post, lawyer Harriet Miers, withdrew when conservatives refused to support her.