TIVERTON — Members of the teachers union, long embroiled in a labor dispute with the School Committee, worked against the reelection of longtime School Committee Chairwoman Denise deMedeiros, who was defeated at the polls on Nov. 4.

The day after the election, the union and the School Committee reached a tentative agreement in nonbinding arbitration on a two-year contract, although the pact has not yet been ratified.

The union did not endorse any candidates for School Committee, according to union president Amy Mullen.

But union members sent copies of a form letter to residents, identifying themselves as teachers in their signatures and urging the recipients, in effect, to vote against deMedeiros.

Without mentioning deMedeiros by name, the letter accused the School Committee and its representatives of trying to avoid public comment and failing to show respect for each other and the school staff.

At various times during the 14 months of the labor dispute, the union and its representatives have been accused of hitting below the belt, most notably when they announced plans to picket deMedeiros at her workplace, the emergency room of St. Anne’s Hospital, in Fall River, where she is a nurse.

The protest never came off, as the venue was switched at the last minute to the office of Schools Supt. William Rearick.

Last week, Rearick acknowledged teachers’ constitutional right to express their views, but he said he took issue with the fact that some teachers tried to influence a local election even though they do not live in Tiverton.

One letter was signed by a teacher he knows does not live in Tiverton, Rearick said.

Union president Mullen, one of those who sent letters, is a Portsmouth resident.

DeMedeiros, who has served eight years on the School Committee, the last six as chairwoman, came in fourth in a field of five in the nonpartisan election for three seats on the board.

Quite apart from the teachers’ letter-writing campaign, deMedeiros was probably hurt by the fact that she spurned the proffered endorsement of Tiverton Citizens for Change, an anti-tax grass-roots political action committee that campaigned intensively for its candidates.

The only TCC-endorsed candidate for School Committee, political newcomer Danielle Coulter, a chiropractor, placed first in the balloting, with 3,135 votes.

Incumbent Sally Black came in about 100 votes behind Coulter. Black, like deMedeiros, declined the TCC endorsement, but unlike deMedeiros, said nary a word about it in public.

One of the teachers’ picks, Carol Herrmann, a public school librarian in Massachusetts and a parent who has frequently attended School Committee meetings, won the third seat, outpacing deMedeiros by 195 votes.

The other candidate pushed by teachers, Deborah Pallasch, trailed deMedeiros by just 39 votes.

The teachers’ letter acknowledged there were three open positions but urged voters to cast ballots only for Herrmann and Pallasch, saying they would ensure that limited funds were spent in cost-effective ways to maintain a quality education.

Herrmann said last week that she and Pallasch had many supporters among teachers because both have volunteered in the schools for many years. She said she and Pallasch ran positive campaigns.

gmacris@projo.com