With his nomination of Samuel Alito to the US Supreme Court on Monday, President George W. Bush has quickly rallied his conservative base to his side.

But he also drew instant criticism from Democrats and liberal groups, who complained that Mr Bush had been motivated to choose Mr Alito to overcome the damage done by the failed nomination of Harriet Miers, his White House counsel and long-time confidante.

The selection has set the stage for a bitter showdown, for which partisans on both sides have long been preparing.

It also raised the possibility that Democrats might seek to block a vote on Mr Alito, returning the Senate to an earlier fight on the treatment of judicial nominees and the rules that govern debate in the chamber.

“Rather than selecting a nominee for the good of the nation and the court, President Bush has picked a nominee who he hopes will stop the massive haemorrhaging of support on his right wing,” claimed Edward Kennedy, the veteran Democratic senator from Massachusetts.

He warned that Mr Alito could put at risk “decades of American progress in safeguarding our fundamental rights and freedoms”.

While Mr Kennedy may have overstated the severity of the wound, there is no doubt that Mr Bush’s selection of Mr Alito – a well qualified nominee with strong conservative credentials – was designed to please conservatives whose worries scuttled the nomination of Ms Miers.

The naming of Mr Alito, just three days after Ms Miers withdrew her candidacy, indicates that Mr Bush accepted pleas from conservative politicians and activists to name someone on the list of candidates they considered fit for the position.

The president won nearly instant praise from some of the conservative critics of Ms Miers.

David Frum, a former speechwriter for Mr Bush, called it “a perfect pick” and seemed to welcome the coming clash over Mr Alito. “There may be a fight over this nomination, but it is a fight that will unite conservatives in support of the president and his fine choice,” Mr Frum wrote yesterday.

Trent Lott, a Republican senator from Mississippi who had said he was uneasy with the selection of Ms Miers, said Mr Bush had “hit a home run” with Mr Alito, and praised the nominee’s judicial philosophy. “He has a well documented understanding of the limited constitutional role of the courts,” Mr Lott said.

Democrats resisted early calls to gauge the level of their disapproval, and whether they would seek to block a vote on Mr Alito.

But Harry Reid, the Democratic leader in the Senate, said he was disappointed for several reasons. He complained that Mr Bush had failed to consult Senate Democrats on the selection, as he had with earlier court choices.

Mr Reid – who had suggested that Mr Bush consider Ms Miers for the Court – said the nomination of Mr Alito “ignores the value of diverse backgrounds and perspectives on the Supreme Court”. Noting Mr Bush’s failure to choose a woman, a Hispanic, or someone who is not already a judge, Mr Reid said: “President Bush would leave the Supreme Court looking less like America and more like an old boys’ club.”

Several people, including Laura Bush, the first lady, had encouraged the president to choose a woman to fill the seat being left vacant by Sandra Day O’Connor, one of only two women on the court.

But liberals were also worried that Ms O’Connor, who had frequently recorded a swing vote at the Court, might be replaced with someone with more reliably conservative views.

“Replacing a mainstream conservative like Justice O’Connor with a far-right activist like Samuel Alito would threaten Americans’ rights and legal protections for decades,” said Ralph Neas, president of People for the American Way, a liberal advocacy group.

Republicans seemed prepared for such criticism.

Minutes after Mr Bush nominated Mr Alito yesterday, the Republican National Committee circulated favourable comments made by several Democratic senators, including Mr Kennedy, when he was confirmed as an appeals court judge in 1990.

Frank Lautenberg, a New Jersey Democrat, said in 1990: “I believe Mr Alito has the experience and the skills to be the kind of judge the public deserves – one who is impartial, thoughtful, and fair.”

Mr Alito is now waiting to see what Mr Lautenberg has to say on Tuesday.