The city’s big labor unions may have dissed Democrat Ruth Messinger, but they are toiling for Eric Vitaliano, a “pro-life” and pro-death penalty Democrat running in the dead-heat Staten Island-Bay Ridge congressional race.

Vitaliano, a seven-term assemblyman, is facing GOP Councilman Vito Fossella, Jr., in a bid to succeed retiring Republican star Susan Molinari. Recent polls have pegged the 13th Congressional District race as too close to call.

Last week, Queens Assemblyman Brian McLaughlin, president of the New York City Central Labor Council, an umbrella organization of city AFL-CIO affiliates, endorsed Mayor Giuliani, joining most other union leaders in supporting the Republican. But McLaughlin’s support of Vitaliano represents labor’s larger anti-GOP push in Washington. “Punishing the national Republicans is only part of the strategy for putting labor issues front and center,” McLaughlin says.

The 13th District’s 73,600 union members give it the highest union density of any congressional district in the state, he says.

Vitaliano, chair of the Assembly’s Government Employees Committee, is cozy with both organized labor and–until this year–the Brooklyn Conservative Party organization, which is no friend of unions. His TV ads call him an “experienced conservative Democrat,” a message intended to fend off a series of negative Fossella ads paid for with $800,000 in contributions from national Republican donors.

Even Larry Hanley, president of the Staten Island-based Amalgamated Transit Union Local 726 and a fixture in liberal county politics, is on board for the right-wing Dem. He says wryly that “Vitaliano is bad on life. He’s bad on death. But once you get past life and death, he’s fine.”

The union push comes after labor’s successful 1995 intervention to stop Borough President Guy Molinari from upending District Attorney Bill Murphy. And union intervention on behalf of Vitaliano was partially responsible for getting Staten Island party head Bob Gigante to abort his own bid for the seat.

Messinger would be lucky to have Vitaliano’s numerous labor endorsements, which include such powerhouses as Hospital Workers Local 1199, District Council 37 and the United Federation of Teachers. Messinger boasts only six union endorsements–the tiny Bridge Painters Union, the Lithographers District 1L, Musicians Local 802, the Tarrytown-based Autoworkers Region 9a, Communications Workers Local 1180 and D.C. 37’s Local 420, a city hospital workers local whose members failed to win job security from the mayor. The rest are either on board for Giuliani or on the fence.