ISLAMABAD, Pakistan, Nov. 9 — The sweeping security crackdown by Gen. Pervez Musharraf that thwarted a protest rally against his emergency decree by the opposition leader Benazir Bhutto left the two adversaries locked in a standoff on Friday.

On the surface, the show of force by the government, which deployed thousands of police officers and other security personnel and confined Ms. Bhutto to her house here for most of the day, appeared to leave the rivals further from a power-sharing deal.

But events did not exclude the possibility that back-channel talks were proceeding, and Bush administration officials said they held out hope that the two leaders could still defuse the crisis that began when General Musharraf declared de facto martial law six days ago.

Some 8,500 police officers locked down Rawalpindi, the planned site of the protest, so completely that only small groups of protesters made it into the city. Dump trucks, tractor-trailers and carts blocked all streets leading to the central square. Riot police officers on motorcycles threatened to beat groups of pedestrians who failed to disperse on command.