Nov. 5 was a good day for the Working Families Party and not only in Connecticut. While the party was taking control of the Bridgeport Board of Education from Democratic Mayor Bill Finch on behalf of its teachers union allies, it was also performing impressively on a larger stage with the election of longtime ally Bill De Blasio as mayor of New York.

The liberal, union-dominated party has become a factor in Connecticut and several other states, not by enrolling members, but playing power broker. It does it by usually endorsing - but occasionally challenging - a Democratic Party candidate and getting pro-union, Democratic voters to vote for their candidate on the Working Families ballot line.

Its greatest Connecticut achievement was in the 2010 gubernatorial election when it induced 26,308 supporters to vote for Democrat Dannel P. Malloy on the WFP line in an election that Mr. Malloy won by only 6,000 votes. This was accomplished by a party that had fewer than 200 registered members statewide.

Democratic legislators showed their appreciation following the Malloy election by passing a Working Families-backed bill requiring businesses with more than 50 employees to pay them when they're sick. Connecticut became the first state in the nation to pass this legislation, which did not destroy small business in the state, as some predicted, but didn't do much for the state's business friendly image either.

Now, the Working Families Party appears to be concentrating on education reform measures that it sees as a threat to one of its most important union allies, the teachers. In Bridgeport, it had to challenge the Democratic establishment as it campaigned successfully for school board seats in a primary and the general election and to oust the reformist school superintendent, Paul Vallas.

Mr. Vallas, appointed by the state after it had taken over the poorly performing Bridgeport schools two years ago, had gained a national reputation as a reformer in Chicago, Philadelphia and New Orleans, but the teachers union disagreed with every move he made, including budget cuts, expanded testing and, of course, teacher layoffs. In addition to trying to remove him by electing a new Working Families school board, the party and the union filed a lawsuit claiming he didn't fulfill certain Connecticut requirements for the position. Last week the state Supreme Court dismissed the lawsuit, unanimously concluding it is not the role of the courts to second-guess whether superintendents meet administrative requirements.

The decision didn't much matter. Before the WFP could celebrate its newly won clout on the Bridgeport Board of Education by firing its longtime nemesis, and before the court could rule, the governor of Illinois announced he was naming Mr. Vallas his lieutenant governor running mate in next year's election.

The goal of seeing Mr. Vallas out of his job had been met in a wholly unexpected manner but the party was in no mood to wish him well.

"Good riddance to Vallas," said Lindsay Farrell, the party's executive director. "We send our regrets to Illinois."

In Illinois, the president of the Chicago Teachers Union, reacted similarly, saying "we are concerned" over the appointment of Mr. Vallas, whose education reform measures as Chicago superintendent resulted in expanded testing, charter schools "and the devastating policy of school turnarounds, which resulted in the firing of scores of black and veteran teachers."

The party and the teachers have derided efforts to turn around struggling schools nationally and locally as "corporate driven," a frequently repeated reference to companies that have financially supported educational reform efforts they see as a way to produce a better educated work force. These efforts have attracted the bipartisan support of political leaders like Mayor Michael Bloomberg of New York, Democratic Sen. Cory Booker of New Jersey and former Republican Gov. Jeb Bush of Florida, hardly a reactionary or anti-education group.

We will be watching the Working Families Party's next moves with interest and some concern. With Bridgeport's school system under its control, will the party and its teachers union allies move on to troubled school systems in other Connecticut cities, large and small, in an effort seemingly designed to protect teachers at all costs? That could be a problem.