TRENTON - Many teachers descended on the New Jersey Statehouse Monday morning to rally support for a proposed amendment ramping up pension payments by the state.

The New Jersey Education Association, the state’s largest teacher’s union, is calling on lawmakers to vote on the proposal.

State Senate President Steve Sweeney last week said that leaders of the teacher’s union called Democratic county chairmen and threatened to withhold political contributions unless the Senate passes the amendment.

Sweeney also called on the U.S. attorney and New Jersey attorney general to investigate the union's action as criminal.

The NJEA said in a statement it did nothing illegal and Sweeney broke a promise to pass the amendment.

Sweeney, an executive with the ironworkers union and possible gubernatorial candidate, called the action "intolerable."

Lawmakers did not vote on the measure Monday. Sweeney says he didn't call the proposal up for a vote because the state hasn't solved its transportation funding problem.

He says transportation funding proposals under consideration could cost the state up to $2 billion a year, in which case it wouldn't be possible to afford the pension payments without painful cuts elsewhere in the budget.

Sen. Sweeney says that the measure can be passed anytime from now until January and still be put on the 2017 ballot.

The Associated Press wire services contributed to this report.