Things didn't go as expected when Gov. Dannel P. Malloy showed up the other day at Nica's Gourmet Market, a deli in New Haven's East Rock neighborhood, to do something governors hardly ever do, interfere in a local party primary by endorsing state Sen. Toni Harp over three other Democrats.

Gov. Malloy had just finished saying New Haven needed a woman mayor, though not saying why, and calling Sen. Harp, the chairwoman of the state senate's appropriations committee, "a monument to the people who care about public service" when an unwelcome guest appeared at the endorsement party.

New Haven resident Wendy Hamilton walked up to the governor and asked a rather embarrassing question about the "monument" he was choosing for mayor: "How can you endorse a candidate whose family allegedly owes a million dollars in sales tax?" Ms. Hamilton asked. "I'd be in prison if I owed a million dollars."

The governor's reply was a classic non sequitur, which is Latin for, among other things, an answer that has nothing to do with the question.

"I don't know a harder working person in the Senate," said the governor as the audience of mostly Harp-supporters gathered around the two, chanting "Toni, Toni, Toni" by way of further explanation. Some interrupted their chants to castigate Ms. Hamilton for bringing up a topic they deemed inappropriate for the solemn occasion.

The million dollars is owed by the business run by Sen. Harp's late husband and now, her son, giving the family of the candidate the dubious honor of being the state's largest tax delinquent. It is a business from which Sen. Harp benefits but she claims it is run without her knowledge or participation. As "proof," she noted she and her husband filed separate income tax returns.

This is the candidate praised by Gov. Malloy for her outstanding handling of taxpayer dollars as chairwoman of appropriations.

The controversies surrounding the Harp finances aren't exactly new. She failed to pay her federal income taxes for four years in the 1990s until her home had a lien placed on it, according to The New Haven Register, which has covered the candidate's 11 terms in the General Assembly.

Fifteen years ago, the newspaper noted, "The senator, as any spouse would, benefits from her husband's gaming the state and city governments - ducking tax bills while winning lucrative contracts worth millions."

So why is the governor not only pursuing the unusual course of taking sides in a primary but choosing a candidate with a shaky resume, to put it kindly? Politics. It has to do with his unannounced, but certain, re-election campaign.

Sen. Harp's generosity in directing taxpayer money to New Haven as appropriations chair has won her the gratitude and support of many interests in the city, most notably its powerful labor unions. As a result, she has the endorsement of the Greater New Haven Labor Council and United HERE, which represents Yale's unionized workers, along with most of the Democratic establishment. That's usually enough to win a primary and an election in Democratic New Haven.

Ms. Harp may or may not need Gov. Malloy's endorsement but the truth is, Gov. Malloy could use hers. In 2010, he won New Haven rather handily, by a vote of 20,848 to 3,679 over Republican Tom Foley, thanks to a superb union-led voter turnout. But Mr. Foley was more successful in the smaller cities and most towns and only lost the state to Gov. Malloy by a few thousand votes and could be his opponent again. The only poll so far, and it's very, very early, has Mr. Foley ahead of the incumbent by three points.

The governor will have to do as well in the Democratic cities, if not a bit better, in 2014 and he knows that the support he can expect from Ms. Harp and her labor allies depends on what Gov. Malloy does for Sen. Harp now.

Her opponents, who include a high school principal and a former city development official, argue the senator's personal financial history makes her an unsuitable choice for the financially troubled city. They're right. That point was underscored when the city that had its credit rating downgraded earlier this month.

Gov. Malloy should have stayed out of this primary, rather than providing this politically self-serving endorsement.