President Bush is evidently considering sending several thousand U.S. combat troops to protect American dependents in Panama, where rioters attacked opposition candidates and the de facto ruler, Gen. Manuel Antonio Noriega, nullified elections.

The assault by Noriega-backed paramilitary forces left the chief opposition presidential candidate with possible brain damage, his running mates wounded and a bodyguard dead.

Pentagon officials who asked not to be identified told The Associated Press the Defense Department has been told Bush "is leaning toward" deployment of 2,000 to 2,500 combat troops to the Canal Zone in Panama to reinforce the American military presence there. But the sources stressed that no final decision had been made and that no "execute order" had been received.

"It looks like its going to go that way; sending down some more troops," the source said. "But there is nothing definite and we're not saddling up the entire 82nd Airborne."

The sources said that if Bush ordered an additional deployment, it would probably be handled as a similar movement in Honduras last year when small units were drawn from both Fort Bragg in North Carolina and Fort Ord in California.

One official called the plan "a show of force that is being orchestrated at the White House. We're not sure about the goals from a military standpoint besides our continuing concern about American dependents."

Rioting broke out in Panama following Sunday's presidential elections, branded as fraudulent by observers and the Bush administration. The opposition claimed victory and Noriega tossed out the election results late Wednesday, hours after armed civilians mobbed and beat several demonstrators in the streets, including presidential candidate Guillermo Endara.

Deputy Secretary of State Law rence Eagleburger confirmed Bush was considering sending American troops into Panama, where about 12,000 military and diplomatic personnel live in and around Panama City.

"We've been waiting to see how the election results came out. It's clear the people want Noriega out," Eagleburger said on ABC-TV's "Good Morning America." "We now have to make our choices on the basis of this robbery that Noriega has perpetrated on his own people."

"General Noriega has thwarted the desire of the Panamanian people for democracy by conducting a fraudulent election," White House spokesman Marlin Fitzwater said Wednesday. Fitzwater and other officials declined to say what options the president is considering, including whether he will beef up the military forces.

Meanwhile, the 10,000 U.S. troops in the Canal Zone were on the second-highest state of alert, and 100 dependents of American diplomats were ordered onto U.S. military bases as a precaution. Two U.S. military attaches were detained by Panamanian police for five hours and were released unharmed.

Yolanda Pulice de Rodriguez, president of the Electoral Tribunal, announced the annulment of Sunday's vote on national radio and television but made no mention of new elections.

Pulice cited a "lack of vote tally sheets, which makes it absolutely impossible to declare winners." She did not mention rampant fraud reportedly carried out by supporters of de facto ruler and military leader Gen. Manuel Antonio Noriega.

Opposition leaders and international observers, including a delegation led by former President Carter and another group sent by President Bush, have accused Noriega's backers of burning and stealing thousands of tally sheets in an effort to switch them with fabricated results.

Most observers agreed the presidential election was won by Guillermo Endara, who was knocked unconscious Wednesday when paramilitary forces using clubs, tire irons and firearms attacked an opposition rally led by Endara and his two vice presidential running mates.

Endara was hospitalized Wednesday night after showing signs of possible brain damage after being struck on the head with an iron bar during the attack by members of the "Dignity Battalions," set up last year by Noriega.

Witnesses said Wednesday afternoon's attack began when 50 men wearing the Dignity Battalions' trademark red T-shirts and caps charged Endara's stalled opposition auto convoy with iron bars, rubber hoses, baseball bats and, on occasion, guns.

Opposition vice presidential candidate Guillermo Ford was dragged from his car, severely beaten and hauled away in a police van, said Endara's other running mate, Ricardo Arias Calderon. Arias Calderon later said Ford may have been arrested.