POLAND — By a vote of 3-2, the Board of Selectmen on Thursday undid the action it took Tuesday and agreed to sign the warrant calling for a June 21 referendum vote on the RSU 16 budget.

The agreement means that the process for approving the 2011-12 school year budget for Mechanic Falls, Minot and Poland schools is once again on track.

Residents of the three towns will meet at 6:30 p.m. Monday, June 13, at Poland Regional High School to debate — town-meeting style — and vote on a budget that will go to a three-town referendum on June 21.

The board reversed itself upon learning from legal counsel and other sources that state law governing how school budgets are approved doesn’t give selectmen the option of whether to post a warrant calling for the referendum.

In answer to the board’s question of what happens if the selectmen don’t sign the warrant, Natalie Burns, the town’s attorney, wrote in her email response: “The RSU can go to court and get an injunction to make you sign and post. If it does so, it will win and you will be forced to sign.”

Poland Executive Assistant Rosemary Roy said the board was dealing with a mandated item.

“It isn’t ‘may’ post the warrant; it is ‘shall’ post,” Roy said.

Selectmen Lester Stevens and Erland Torrey switched their votes, but made it clear that they did not support the school budget at the $17.9 million level. The RSU School Committee approved the amount Monday night.

“A lot of townspeople assume that when we sign a warrant, it means we support it. That is not the case,” Torrey said.

Selectman Steve Robinson, who Tuesday cast the lone vote in favor of signing the warrant, repeated that he was voting to do so because “that is what the process calls for.”

Selectmen Larry Moreau and Wendy Sanborn maintained their refusals to sign.

“I don’t feel any different,” Moreau said. “The system is broken and needs to be fixed.”

Sanborn wanted it known that it was not her intent to deny folks a right to vote, but that there was something fundamentally wrong with the situation she found herself in, where she, as she saw it, was being “forced” to “endorse” something.

“If the referendum is a mandate, why should we be mandated to sign?” Sanborn said.