ALBANY — The State Senate, dark since Monday's GOP-led coup, went back into session today, but quickly ended when one of two Democrat dissidents walked off the floor, saying he would not return until more Democrats joined the takeover group.

With protesters from Democratic-leaning groups trying to block lawmakers from entering the chamber, the session fell apart immediately when the official bills that the Senate was about to move to the floor were locked in a desk by Democratic officials seeking to prevent the Republican-backed coup group from voting. Republicans did not have keys to the desk.

Sen. Hiram Monserrate, a Queens Democrat who is considered the weakest link in the uprising, walked out of the session — which left not enough members to have a quorum to take up any business. He said he needed more Democrats to join the takeover effort to make it a true coalition Senate.

"This chamber must not remain divided, so I'm going to excuse myself from this chamber," he said.

The on-again, off-again supporter of the coup said he will not return until the coalition expands. That leaves the Senate in a complete standstill with neither side able to produce the 32 votes needed to call session.

"You can't have a coalition government with two Democrats and 30 Republicans," Monserrate told reporters after leaving the session.

Sen. Pedro Espada, elected president of the Senate Monday by Monserrate and 30 Republicans, insisted the coup is not falling apart. He predicted more Democrats would join the effort, especially after a state Supreme Court judge refused this morning to issue an injunction to undo Monday's takeover by the GOP-led group.

"My engines will never be on reverse here," he said after the collapsed Senate session, which the group wanted to hold, in part, to show they were in control of the 62-member house.

Espada also said there has been criminal harassment engaged by unnamed people trying to turn back the coup. He said his Bronx house was burglarized Monday night — just hours after he led the coup — and various files in his home office were stolen.

Espada said earlier that Senate Democrats asked Gov. David A. Paterson to change the locks on the Senate chamber to keep out the coup backers; the Democratic governor rejected the idea.

The governor also halted a request that a top Senate Democratic official made to the superintendent of the State Police to send troopers to guard the Senate doors, two state officials said.

Later Wednesday night, Senate Democrats met in an Albany restaurant to plot strategy and to consider their own coup against Malcolm Smith, the Queens Democrat who served as majority leader for six months.

With a packed crowd waiting to see how the GOP lawmakers would enter the locked chamber, GOP senators were kept waiting more than an hour by Monserrate for a private meeting.

“There’s no problem,” said Monserrate, heading to the meeting.

Monserrate urged Skelos and Espada to hold off on conducting the session because he was convinced Smith was going to be dethroned. The power play for Smith’s job between two New York City Democrats would leave some other Democrats disgruntled, he told them, making opportunities for more to join the Senate overthrow.

The coup leaders are hoping to add more Democrats, in part, to weaken the argument that 30 Republicans and two party-bending Democrats make a coalition.

The pressure to flip — and not flip—is on Sen. William Stachowski, a Lake View Democrat. Sources close to Espada said Stachowski, if he flips, has been offered the chairmanship of the Senate Finance Committee — a job he was promised, but not given, last year by Smith.

Stachowski did not return calls seeking comment.

“I’m not a bit worried about him defecting,” said Leonard Lenihan, the Erie County Democratic Party chairman, who noted, however, he has not had direct talks with Stachowski.

“I strongly recommend Sen. Stachowski get on board and help this community,” countered Anthony Baynes, an Amherst businessman who helped advise Monday’s coup. “Sen. Stachowski has an opportunity to step up to the plate and help Buffalo and Western New York.”

Democrats, including Smith, remained out of sight for most of Wednesday.

“We were told there was going to be a session. There was none. I generally don’t comment on non-occurrences,” said Austin Shafran, a Smith spokesman.

Skelos, in a hallway interview Wednesday, insisted the coup is not unraveling and said an extra day was given to give on-the-fence Democrats time to think through their decision.

“It’s a tough decision,” he said.

Paterson, meanwhile, sent a mixed message.

Though condemning the coup as “an insult to government,” he offered no specific backing to Smith and said he would be willing to meet with Espada and Skelos, who had been majority leader until earlier this year when the Democrats took over.

He also suggested a working coalition could lead to some of the plans he wants — such as a property tax cap — that have so far been blocked.

Though he is the leader of the Democratic Party, Paterson said he is not twisting any arms to keep the Democratic peace in the Senate.

“I’m not going to interfere in what goes on in the legislative branch,” he said.

Later, in Clarence, Paterson said he believes the fight should be resolved on the Senate floor and not in a courtroom.

“Then we can get back to government,“ he said. “Whoever wins, wins. Whoever loses, loses.”

Perhaps the most-asked question of the day amid the nonstop hallway chatter in the Capitol was:

“Have you ever seen anything like this before?”

Blair Horner, a lobbyist with the New York Public Interest Research Group, said the Capitol will remain on a roller coaster ride for the time being.

“In Albany, the waters of conspiracy run deep, so who knows what’s really going on?” he said.