PORTLAND – The union representing Maine teachers on Tuesday endorsed Democrat Chellie Pingree in her Senate bid. Republican Sen. Susan Collins responded by announcing the formation of an “Educators for Collins” group independent of the Maine Education Association.

The Maine Education Association, which has 25,000 members, did its “homework” and concluded it could count on Pingree, who is trying to unseat Collins, said Rob Walker, the union’s president-elect.

But Collins said MEA members who endorsed fellow GOP Sen. Olympia Snowe in 2000 didn’t get to cast their votes this time.

The MEA changed its endorsement process this year to allow union leaders to cast tallies after face-to-face discussions with candidates instead of putting the endorsement to a vote by the full membership.

“We’re confident that if it had been put to a vote of all MEA members, that Sen. Collins would have received the endorsement,” said Megan Sowards, spokeswoman for the Collins campaign.

Mark Gray, the MEA’s executive director, insisted the endorsement reflected the view of the majority of members.

Gray, Walker and more than 40 teachers joined Pingree at a news conference announcing the endorsement at Nathan Clifford School, an elementary school in Portland which Pingree says is one of many in need of improvement.

Pingree described herself as an education leader in the Legislature and in her North Haven island school district.

“I will always put the needs of Maine’s children above tax cuts for the wealthy and Washington special interests,” she said.

Before the event was concluded, the Collins campaign had issued a rebuttal that cast her as the best candidate on education and announcing “Educators for Collins,” which included several MEA members.

Sowards said the MEA endorsement was politically motivated. She noted that the MEA did not endorse Republican candidates for governor or for federal office. Its parent organization, the National Education Association, also is not supporting any GOP Senate candidates, she added.

The nine leaders of “Educators for Collins” contacted the Collins campaign because they were unhappy with the MEA endorsement, Sowards said. Dozens have joined the group, and a membership list will be released this fall, she said.

Deborah Barron, spokeswoman for Pingree’s campaign, declined to comment on the new group formed by Collins’ campaign.

“We have the MEA and that stands. It’s the largest education group in the state,” she said. “The endorsement speaks volumes.”

Gray said the endorsement was narrowly focused on the issue of education – not politics – and that Pingree came out on top.

The new system, he added, is an improvement over the old system in which transcripts of candidates’ comments on education were mailed to individual members, who voted by mail, Gray said.

In the past, so few mail-in ballots were returned to the MEA headquarters that the results had become unreliable, Gray said. Also, leaders feared the process was being transformed into a popularity contest instead of focusing on issues important to educators, he said.

“This wasn’t a popularity contest. It was a serious effort to identify the candidate who best reflected our position on education issues,” he said.