ALBANY — A rogue Queens Democrat who last week flipped sides to help Republicans take control of the State Senate has now flipped back back to the Democrats — creating an historic, gridlock-producing 31-31 tie in the 62-member house.

Because there is no lieutenant governor — David A. Paterson was elevated last year following disgraced former Gov. Eliot Spitzer's departure — no one is quite certain how, or even if, dozens of must-do bills will get passed in the coming weeks.

The situation has created a constitutional crisis in which the Legislature is effectively shut down from approving new bills just a week before the scheduled end of the 2009 session.

Sen. Hiram Monserrate, a Queens Democrat, said today he has returned to the Democratic conference he bolted from last week.

"We've got to take back the Senate," said Monserrate as he stood next to his fellow Democrats this afternoon. Only a week ago, he stood in the back of the Senate chamber and voted for the GOP takeover.

"This conference today is more unified than ever," Monserrate said.

Depending on the outcome of a pending court case over whether the leaders backed by the Republicans or Democrats are in control, the Democrats agreed to keep Sen. Malcolm Smith as the president and majority leader of the Senate. That's because, with a 31-31 tie, he cannot be replaced since it takes 32 votes of the Senate to elect a Senate president.

In effect, if the Democrats win their court case, Smith will be leader in name only. In his place serving as leader of the Democratic conference in a chief executive officer-type position is Sen. John Sampson, a Brooklyn Democrat.

It was uncertain how the Senate can go into session today, given the stalemate. Smith and Sampson have reached out to Sen. Dean Skelos, the head of the Republican conference, to try to work out some sort of power-sharing arrangement. How that will work — given the mistrust on both sides and even within the Democratic conference — remains Albany's biggest question.

Soon after Monserrate announced his Democratic return engagement, a state judge put off until Tuesday a decision on whether last week's coup was illegal.

And at the Capitol, Paterson was planning to call a meeting of the Senate's battling leaders to try to work out some sort of power-sharing arrangement. But, in the end, the governor has no legal say in the matter.

The switch back had been expected since Monserrate last Thursday publicly questioned the coup that was put together, saying it did not represent a true coalition with 30 Republicans and two Democrats. Monserrate was under intense pressure to reverse his decision, with robocalls blanketing his district to get voters to press him to rejoin the Democratic conference. Hundreds of protesters turned out in front of his Queens home one night last week.

"He can't even return home," a Democratic lawmaker said at the time.

Up in the air is a range of big and small bills, from efforts by Paterson to do something to control the growth of property taxes to a new construction plan by the Buffalo city schools. Also, counties around the state are waiting on Albany to pass various local bills, especially extensions to laws allowing them to collect additional sales taxes in order to balance their budgets.

The sides were back in court today, waiting a decision by Supreme Court Judge Thomas McNamara over whether last week's coup was legal. Democrats contend the surprise takeover last Monday was illegal because the session had been adjourned. Republicans insist the house was still in session because a legal adjournment vote did not occur.

With a 31-31 tie, the judge's decision becomes that much more important because it will determine which party will be in control of the Senate president's post — a job that not only handles office and staff assignments and the flow of money from the Senate but is also first in the line of succession if the governor leaves office.

This morning, McNamara told the two sides that courts in New York only have gotten involved in internal matters affecting the Legislature "with great reluctance." This afternoon, he told them to return to the Capitol to continue talking; he ordered them back in his chambers Tuesday morning.

The judge ordered the Democrats and Republicans to go back across the street to the Capitol to try to resolve their differences. He gave them until 1 p.m. "As a matter of public policy, you guys should work this out," the judge said.

Republican lawyers declined to discuss the judge's ruling in any detail.

But a lawyer for the Democrats noted the historic dilemma the Senate is now facing. "Under the circumstances of a 31-31 tie, nobody's going to have a quorum to begin a session at any moment, so there must be a power-sharing agreement for the Senate to operate," said Richard Emery, a Manhattan lawyer representing the Democrats.

"That requires a lot of negotiations, a lot of give and take between the parties and, hopefully, that's what's about to happen. The judge is looking forward to progress on that front," he added.

Asked if a power-sharing deal is possible, Emery said, "We'll see. I'm not the expert in whether 31-31 can work. I don't think anybody is. It's unprecedented."

The two dissident Democrats are facing pressure outside Albany. Prosecutors are looking at whether Espada illegally claims his Bronx home as his residency instead of a Westchester County house, which was broken into last week following the coup. Health clinics founded by Espada are also under investigation to determine if state money may have improperly flowed to the facilities.

Monserrate, meanwhile, has been indicted for slashing the face of his girlfriend with a broken glass.