New York State Senate Democrats are furious today over an unprecedented agreement reached by Republicans and conservative-leaning Democrats who disbanded from their party to form their own caucus.

The move forms a "bipartisan governing coalition" between Republicans and the Independent Democratic Conference, just a month after Democrats won a numerical majority in the chamber.

Under the agreement, Republicans and the IDC will shift control every two weeks between GOP Leader Dean Skelos and IDC Leader Jeffrey Klein. On Tuesday, Sen. Malcolm Smith, a Democrat from Queens, became the fifth Democrat to defect and join the IDC.

The other Democrats, obviously, are not happy about this. On Election Day, they had won several close races that put them in position to take control of the Senate. But Democratic Sen. Simcha Felder, of Brooklyn, soon announced that he would caucus with Republicans, The New York Times reported. And behind the scenes, the five Democrats were working to form a permanent IDC.

Here's a full statement from Senate Democratic spokesman Mike Murphy:

“This is not a coalition but a coup against all New Yorkers who voted for Democratic control of the Senate and a progressive state government.

Sadly, the real victims of today's announcement are the people of our State, whose clearly expressed desire for progress on a host of issues will now be scuttled. Senate Democrats will remain fierce advocates for them and the issues New Yorkers want to see implemented like standing up for women’s health, passing real campaign finance reform, raising the minimum wage and enacting common sense gun laws.”

In a joint statement, Skelos and Klein said the deal “guarantees a fiscally responsible, fully functional Senate that will continue to produce positive results for all New Yorkers."

The move might result in more criticism for New York Gov. Andrew Cuomo, who has come under fire from progressives who say he hasn't done enough to help elect Democrats in his state.