A delegation of conservative lawyers met the White House chief of staff, Andrew Card, last week to make it clear they would not support Mr Gonzales's nomination because his stance on abortion and affirmative action was unclear.

"We would oppose him because we don't believe he has a philosophy that we can determine. We are not enthused," Tom Minnery, vice-president of public policy for the conservative Focus on the Family, told the Washington Post. "He is someone who is apparently still developing his philosophy and that is not good enough."

In his current post of attorney general, Mr Gonzalez is responsible for screening potential nominees to replace Ms O'Connor, whose resignation on Friday caught Washington by surprise.

Yesterday, during a quick visit to Iraq, Mr Gonzales deflected speculation about his intentions. "Many of the people speaking probably don't have all the information about prospective nominees. What is important is what the president of the United States thinks about me," he told the Associated Press. "That's evident by the position he has asked me to fill."

Asked if he is flattered to be considered, Mr Gonzales said: "I just look at the job that I do as attorney general. I'm happy in that job."

Mr Gonzales, who would be the first Hispanic supreme court judge, would also face a tough challenge from Democrats for his position on torture. He encountered a bruising, but ultimately successful, nomination for attorney general earlier this year, after he described the Geneva conventions' rules on the questioning of enemy prisoners as "obsolete" and other aspects of the conventions as "quaint".

He was confirmed to the post of attorney general by a vote of 60-36 which was divided largely on partisan grounds; by contrast Ms O'Connor was confirmed in 1981 by a vote of 99-0.

The right is concerned that, once appointed, Mr Gonzales might drift towards a liberal stance on issues such as abortion. They point to other supreme court judges, such as David Souter and Ms O'Connor, appointed by George Bush Sr and Ronald Reagan, as examples of judges who despite conservative credentials ended up too liberal for their tastes.

They would like to see Mr Bush nominate a candidate in the mould of the two most rightwing judges, Antonin Scalia and Clarence Thomas.

"The only nomination that would cause the people that I really associate with consternation would be Gonzales," said Michael Farris, a conservative constitutional lawyer. "The president is going to need all the help he can get no matter who he picks. I don't think many people in the socially conservative movement would openly oppose him, but the enthusiasm would be sufficiently dampened to the point that many would not participate."

These warnings were the first of many salvoes to come in the battle over the supreme court vacancy, which will intensify if another judge, supreme court Justice William Rehnquist, also resigns over the summer, as is expected.

Mr Bush has to balance the prospect of dividing the nation with the possibility of alienating the fundamentalist, Christian base which supported him in such numbers during the presidential election and now seek payback.

"Conservative groups believe that the president should just do what he promised," said the Alabama republican senator Jeff Sessions, who would like to see a candidate to the right of Mr Gonzales.

"He was crystal clear on his vision of the appropriate qualities of a judge," he said. "He can't allow personal or short-term political factors to override his commitment."