Two conservative Democrats in the Washington state Senate have abandoned their party to caucus with Republicans, effectively giving the GOP control of the upper chamber. 

Democrats hold 26 of 40 seats in the Senate, but Sens. Rodney Tom and Tim Sheldon have given the Republican caucus a 25-to-24 edge. 

"It is time we put aside party dynamics and focus instead on the needs of all Washingtonians," Tom said in a statement. Republicans have promised to make Tom majority leader, a move that requires rewriting the Senate rules from the floor when the new legislature convenes in January. 

Last spring, Tom, Sheldon and departing Sen. Jim Kastama joined with Republicans to push through a budget plan over Democratic objections, a coup that rocked the legislature. 

Democrats still hold a comfortable majority in the House, as well as the governor's mansion.