AFL-CIO President Richard Trumka predicted Wednesday that — unless Republicans back down first — Senate Majority Leader Harry Reid, D-Nev., will hold a vote to change the chamber’s filibuster rule.

The union leader said at an event hosted by the Center for American Progress Action Fund that he expects the Democrats will come out of a caucus meeting set for Thursday “unified” on the issue and will make an ultimatum to the Republicans.

The Democrats’ ultimatum to the GOP would be: “This is about obstructionism and if you continue to obstruct, we will use the rules to force you not to obstruct.”

Big labor has been aggressively pushing Democrats  to change the filibuster rule. They are upset over both the lack of action on President Obama’s pick for Labor Secretary Thomas Perez, and the the five nominees for the National Labor Relations Board.

UPDATE: Fred Wszolek, spokesperson for the pro-business Workforce Fairness Institute issued the following statement in reaction to Trumka’s comments:

Today, Big Labor gave a direct order to the leadership of the United States Senate.  Richard Trumka told Senate Majority Leader Harry Reid to ‘pull the trigger’ on the so-called nuclear option. Union bosses believe they are owed ‘payback’ for the hundreds of millions of dollars they have spent on politics.  The time has come for labor’s allies in the Senate to make a choice: do they represent the American people or are they a wholly-owned subsidiary of a special interest?