HONG KONG — Hong Kong student protest leaders vowed Wednesday to stay until the last minute and peacefully resist a police operation to clear them off a highway where they've been camped out for 2 1/2 months.

Thousands of protesters and supporters streamed into the site on the last night of what's come to be known as the "Umbrella Movement," named for the pro-democracy protesters' preferred method of deflecting police pepper spray.

Many huddled in the hundreds of tents that remained on the normally busy thoroughfare outside of the specially administered Chinese city's government headquarters, less than a day before court workers assisted by police were scheduled to sweep them out. Others took photos, listened to speeches and lined up for souvenir leather bracelets and other mementos handmade on the spot by volunteers.

Two student groups that have played key roles in organizing the protests called for supporters to join them at the site before midnight, when police were rumored to be planning to seal off the area. Police, however, denied there was any such plan and said they would move in at 9 a.m. Thursday.

"We will still resist till the last moment," said Alex Chow, secretary general of the Hong Kong Federation of Students. He said the reason for staying until the end is "not simply for us be arrested, but to demonstrate our spirit" of civil disobedience.

Joshua Wong, the 18-year-old head of the Scholarism group and the pro-democracy movement's most prominent leader, urged supporters to stick to their nonviolent principles and not obstruct court workers or police.

"If the government wants to use police to clear the site, don't forget, the clearance can't resolve political conflicts, it can't resolve society's dilemma," he said.

Authorities will start by removing barricades and other obstructions from three sections of road covered by a court order. Then they will clear other nearby blocked roads to reopen the entire area to traffic. Anyone who refuses to leave the road will be arrested, police said.

While some protesters had already packed up their belongings on Wednesday, many promised it would not be the end of the pro-democracy movement, using large yellow banners, chalk scrawled on asphalt or balloon letters stuck on a wall to declare "We'll be back."

The sprawling encampment in Hong Kong's Admiralty neighborhood, on the edge of the financial district, has become the symbolic nucleus of the protest movement, now in its 74th day.

On Sept. 28, thousands of protesters angry over the prolonged detention of key student leaders swarmed onto the road to confront police, who fired dozens of tear gas rounds in a bid to disperse them. But that only stoked further public anger and kick-started the pro-democracy movement, which came to include two other protest sites in Hong Kong.

The protesters reject Beijing's restrictions on the first election for the city's top leader, scheduled for 2017, but have failed to win any concessions from Hong Kong's government.

"When they come tomorrow, I feel it will be such a pity," said Pang Tsz-kwan, a 35-year-old clerk. "We've stayed for such a long time in this place that I've come to feel deep affection for it and I'm unwilling to leave."

"I hope to stay until the last second," added Pang, who said he would volunteer with first-aid teams to assist anyone injured in the operation.

Hong Kong's second-highest ranking government official, Chief Secretary Carrie Lam, stepped up pleas for protesters to leave the site, warning people not to heed student leaders' calls to return to the scene.

"This is most undesirable, because once the police operation is underway, and knowing very well that there are some radical elements amongst the protesters, confrontation might become inevitable," Lam said.

The government said the headquarters complex would shut down Thursday and that 3,000 staff would not need to come to work.