WASHINGTON — President Bush, in a constitutional showdown with Congress, claimed executive privilege Thursday and rejected demands for White House documents and testimony about the firing of U.S. attorneys.

His decision was denounced as "Nixonian stonewalling" by the chairman of the Senate Judiciary Committee.

Bush rejected subpoenas for documents from former presidential counsel Harriet Miers and former political director Sara Taylor. The White House made clear neither one would testify next month, as directed by the subpoenas.

Presidential counsel Fred Fielding said Bush had made a reasonable attempt at compromise but Congress forced the confrontation by issuing subpoenas. "With respect, it is with much regret that we are forced down this unfortunate path which we sought to avoid by finding grounds for mutual accommodation."

The assertion of executive privilege was the latest turn in increasingly hostile standoffs between the administration and the Democratic-controlled Congress over the Iraq war, executive power, the war on terror and Vice President Dick Cheney's authority. A day earlier, the Senate Judiciary Committee delivered subpoenas to the offices of Bush, Cheney, the national security adviser and the Justice Department about the administration's warrantless wiretapping program.

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Supreme Court rejects public school diversity plans that take race into account

WASHINGTON — A half-century after the Supreme Court outlawed segregated schools, sharply divided justices clamped new limits Thursday on local school efforts to make sure children of different races share classrooms.

The court voted 5-4 to strike down school integration plans in Louisville, Ky., and Seattle, a decision that imperiled similar plans that hundreds of cities and counties use voluntarily to integrate their schools.

The ruling does not affect several hundred other public school districts that remain under federal court order to desegregate.

Justices disagreed bluntly with each other in 169 pages of written opinions on whether the decision supports or betrays the landmark Brown v. Board of Education ruling that led to the end of state-sponsored school segregation in the United States.

The 5-4 decision, the 24th such split this term, displayed the new dominance of the court's aggressive conservative majority. The four liberal justices dissented.

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Bombing kills 22 at Baghdad bus station; officials investigate report of decapitated bodies

BAGHDAD — A car bomb exploded Thursday at a bus station in a mostly Shiite west Baghdad neighborhood, killing 22 people. Officials received word that 20 decapitated bodies had been found near the capital but were unable to confirm the report because of fighting.

In addition to the dead, more than 50 people were wounded in the rush-hour blast in the Baiyaa neighborhood, police said on condition of anonymity because they were not authorized to release the information.

A huge fireball incinerated about 40 minibuses as people were lining up to catch rides to work, police and survivors said.

Associated Press Television News video showed the area littered with smoldering vehicle parts and charred bodies — their clothing in tatters. Bystanders, some weeping, gingerly loaded human remains into ambulances and pickup trucks.

No group claimed responsibility for the blast, but suspicion fell on Sunni militants.

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Democratic presidential candidates to debate racial issues, struggles of black America

WASHINGTON — The struggles of the nation's blacks — a loyal Democratic voting bloc — topped the agenda Thursday as the party's eight presidential candidates gathered for their third primary debate.

The debate at Howard University was scheduled to begin just hours after the Supreme Court ruled against public school programs aimed at achieving racial diversity, a certain topic for the event.

The Democrats decried the ruling, saying it turned back the promise of integrated schools that the court laid out 53 years ago in its landmark decision in Brown v. Board of Education.

New York Sen. Hillary Rodham Clinton said as president, she would "fight to restore Brown's promise." Illinois Sen. Barack Obama said it was "wrong-headed." Connecticut Sen. Chris Dodd said the decision "will add to the resegregation that is already occurring in our nation's schools."

John Edwards said the decision showed what is at stake in the presidential race.

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As desertions rise, U.S. military makes little effort to track down those who flee

FORT BRAGG, N.C. — There is no crack team of bounty hunters, no elite military unit whose job is to track them down and bring them in.

Despite a rise in desertions from the Army as the Iraq war drags on into a fifth year, the U.S. military does almost nothing to find those who flee and rarely prosecutes those it gets its hands on.

An Associated Press examination of Pentagon figures shows that 174 troops were court-martialed by the Army last year for desertion — a figure that amounts to just 5 percent of the 3,301 soldiers who deserted in fiscal year 2006. The figures are about 1 percent or less for the Navy and the Marines, according to data obtained by the AP under the Freedom of Information Act.

Some deserters are simply allowed to return to their units, while the majority are discharged in noncriminal proceedings on less-than-honorable terms.

Pentagon officials say that while the all-volunteer military is stretched thin by the fighting in Iraq and Afghanistan, the number of deserters represents an extremely small percentage of the armed forces, and it would be a poor use of time to go after them, particularly when there is a war on.

As a result, the Pentagon does little more than enter deserters' names into an FBI national criminal database.

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Domestic cats may be traced to wild progenitors that interbred 100,000 years ago

WASHINGTON — Garfield, Morris and the Aristocats get the fame, but look to the origins of today's furry felines and you find "lybica," a Middle Eastern wildcat. Domestic cats can be traced to wild progenitors that interbred well over 100,000 years ago, new research indicates.

"House cats — which includes fancy breeds and feral cats — those cats all form a genetic group that is virtually indistinguishable from ones in the Middle East," said Stephen J. O'Brien of the National Cancer Institute.

"So, domestication, for sure, took place in the Middle East where those cats live today," added O'Brien, co-author of a paper appearing in this week's online edition of the journal Science.

Carlos Driscoll, of Oxford University and NCI, and an international team of researchers studied the origins of those loving and aloof, graceful and finicky pets that entertain or supervise millions of homes.

It's serious research, because cats are a model for some human genetic diseases, such as polycystic kidney disease and retinal atrophy, Driscoll explained in a telephone interview. In addition, the work is expected to assist in conservation efforts for wild cats, he said.

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Tony Parker says the cake for his wedding to Eva Longoria will be made in France

PARIS — For Tony Parker, only French-made wedding cakes will do. The NBA champion, set to marry "Desperate Housewives" star Eva Longoria next week, is staying coy about plans for the event.

Speaking to reporters Thursday in Paris, the San Antonio Spurs point guard shrugged off questions about the wedding date and venue, believed to be July 7 at a French chateau.

"I don't care where I'm going to get married," he said. "It's a girls' thing." To other queries, he replied: "That's a question you should ask Eva."

He dismissed one rumor: that the wedding cake would be flown in from the United States.