John Walker Lindh (search) asked President Bush on Tuesday to commute his 20-year prison sentence for aiding the Taliban.

His lawyer, James Brosnahan, said that Lindh was fighting alongside the Taliban (search) in a civil war against the Northern Alliance, that he is not a terrorist and that he never fought against U.S. troops.

Brosnahan said the sentence should be reduced because Yaser Esam Hamdi (search), another American citizen captured in Afghanistan on suspicion of aiding the Taliban, is being released after being held for three years as an enemy combatant.

Hamdi will not be charged with any crime under an agreement with federal officials made public Monday. Hamdi will be required to give up his U.S. citizenship and will be sent to Saudi Arabia, where he grew up.

"Comparable conduct should be treated in comparable ways in terms of sentencing," Brosnahan said at a news conference.

The White House referred calls to the Justice Department. Justice Department spokesman Mark Corallo, while not commenting directly on the merits of Lindh's request, pointed out that Lindh "pleaded guilty to supporting the Taliban with his lawyers standing beside him."

"The Taliban was a brutal regime that harbored and assisted Al Qaeda," Corallo said. "It should be pointed out we are currently engaged in a global war on terrorism against Al Qaeda and remnants of the Taliban."

Lindh's request does not specify how much of a reduction he is seeking.

Lindh, a 23-year-old Northern California native, pleaded guilty in civilian court to supplying services to the now-defunct Taliban government and carrying explosives for them. He and Hamdi were both captured in late 2001.

Brosnahan said he negotiated the 20-year sentence during a time when a "highest state of fear" was affecting U.S. juries and he thought it was the best deal he could get at the time. He could have gotten life in prison if convicted.

Frank Zimring, a University of California, Berkeley, legal scholar and an expert on clemency, said it is unlikely the president will reduce Lindh's term, especially during a presidential election focused on the war on terror.

"The morning line on the commutation of a sentence of this kind in a middle of a presidential election is one of those situations where London bookies would offer you millions of pounds for just a shilling or two," he said.

Lindh's mother, Marilyn Walker, said her son "has never had any sympathy or involvement in terrorist activity."

In all, the president has commuted the terms of two prisoners, both on May 20.

The president commuted the sentence of Bobby Mac Berry, of Burlington, N.C., who had been sentenced to nine years in prison in 1997 for marijuana and money laundering convictions.

Bush also commuted the sentence of Geraldine Gordon, convicted in Las Vegas of a drug distribution charge in 1989 and sentenced to 20 years in prison. Gordon's release was effective Sept. 20.