Mr DeLay appeared in a court in Austin, Texas for the first time since his indictment on conspiracy and money laundering charges.

But his formal charging - known as an arraignment in the US - was delayed pending a hearing on a request from his lawyer for a new judge to be appointed to the case.

During today's brief hearing, the congressman's lawyer Dick DeGuerin said Judge Bob Perkins had donated money to MoveOn.org, a 'liberal political campaign group', whose website had been selling T-shirts bearing an image of his client.

The judge said he had not seen or bought such a T-shirt and could not recall donating to the group since before the 2004 election, "when they were helping [Democrat presidential candidate] John Kerry".

He said the best way to handle the request for a new judge would be to adjourn the proceedings. It was not clear when a hearing would be held to settle Mr DeGuerin's motion.

Mr DeLay, who was photographed and fingerprinted yesterday at the Harris County sheriff's office and released on £5,600 bail, did not speak during today's 10 minute hearing and was not called on to make a plea.

At a news conference outside the courthouse, Mr DeGuerin said: "All we want is a fair trial before a fair tribunal."

But prosecutor Ronnie Earle, whom Mr DeLay has repeatedly denounced as a Democratic partisan, brushed aside the request for a new judge.

"What this means is if a judge had contributed to Crime Stoppers that judge could not hear a burglary case," Mr Earle said. "Carried to its extreme, that is what I think this motion means and I think that's absurd. We don't live in a country where political party determines the measure of justice."

Until the charges were announced, Mr DeLay was the Republican leader in the House of Representatives, the second most powerful position in the chamber. A close George Bush ally, he was forced under the chamber's rules to stepped aside from his role as majority leader to fight the allegations.

He is known for his conservative politics and fundraising and has been a central figure in securing the current Republican domination of Washington and its lobbying system.

Mr DeLay and two political associates are charged over an alleged scheme to launder £108,00 by funnelling corporate donations to Republican candidates for the Texas legislature. State law prohibits the use of corporate donations to elect or defeat state candidates. All three deny wrongdoing.

The charges arise from a campaign in which Republicans gained control of the legislature, then used their new majority to force through a redistricting plan that won the party additional seats in the House of Representatives.

The court proceeding comes at a time when Mr Bush's popularity is at a low ebb and the Republicans beset by other ethical or criminal investigations, including stock sales by the party's senate leader, Bill Frist, and a grand jury inquiry into whether top Bush administration aides leaked the name of a covert CIA officer.