Local One, the IATSE union that includes Broadway stagehands, made a show of force Tuesday, picketing in front of Gotham venue Merkin Hall when contract talks with the venue’s management stalled.

Members of Local One — the union whose strike shut down most of Broadway as part of a 2007 labor dispute — plus members of the Theatrical Teamsters union gathered in barricaded groups in front of the venue, with a turnout in early afternoon that looked to number well over 100. Two giant inflatable rats, a favorite shaming tactic of New York unions, were trotted out.

According to both sides, the dispute boils down to a no-strike, no-lockout clause that would remain in effect for the duration of the new agreement. To hear the union side tell it, Local One generally doesn’t include such clauses in its contracts but agreed to one, at management’s insistence, with the stipulation that should another IATSE union call a strike, Local One would, according to IATSE regulations, be required to honor it.

It’s that codicil to which management at Kaufman Center, of which Merkin Hall is one division, objects.

Both sides say that all other aspects of the new labor contract have been agreed on, including benefits and pay increases. Some elements of the discussed contract have been implemented already, and the union allowed members to work Tuesday despite the picket line.

The standoff seems prompted more on principle than by the size of the deal on the table. Performance venue Merkin Hall, which presents live entertainment and concerts including a series featuring Broadway fare and performers, semi-regularly employs a core group of only half a dozen stagehands, with those numbers bumped up periodically based on the requirements of a particular show.

Local One plans to hold a similar rally Wednesday, with the two-day demonstration timed to coincide with the load-in of the next installment of the Intelligence Squared debates.

The union said backing down wasn’t an option. “The concept of Local One walking through a sister union’s picket — it’s just not going to happen,” said Local One prexy James J. Claffey Jr.

Management held similarly firm. “Kaufman is insisting on an unconditional no-strike, no-lockout clause. We need labor peace throughout the duration of the agreement,” said Lydia Kontos, exec director of the Kaufman Center. “For now, our programs are continuing.”