But it also set the state chairmen of these long-linked parties on the kind of collision course that has smashed up statewide GOP candidacies in past elections.
Lazio pledged to stay in the race through November even if he loses GOP support, Long noted. And the executive committee that voted to endorse him controls whether a nonparty candidate like Levy can run a Conservative primary against Lazio.
Ed Cox, the first-year state Republican chairman, backed Levy on Friday as the Democratic Suffolk executive signed off on his stunning party switch to the GOP.
Thus the threat of schism grows on the political right - at least in this one race in Democratically dominant New York.
In governor's races, their degree of unity can be crucial.
In 1990, Long and company rejected the Republican challenger to Gov. Mario Cuomo and endorsed Herbert London - who garnered 827,614 votes to Republican Pierre Rinfret's 865,948 as Cuomo was re-elected.
But just four years later, Cuomo was ousted by George Pataki's unified Republican-Conservative candidacy.
Speaking on the sidewalk on 78th Street in Bay Ridge, Lazio sounded as if he was trying to catch up a bit with Levy in the emphatic-speech department.
"Today was a huge step forward for us to secure the nomination of the Conservative Party and the Republican Party," he said in a rapid-fire delivery. "We are going to talk about the fact that we're going to restore fiscal sanity to a state that has gone off the deep end . . . we're going to take on the special interest and lower taxes."
Levy, who along with Suffolk Conservative chairman Ed Walsh appealed to Long to delay the endorsement, tried to downplay the vote as "merely an unweighted suggestion." He said he expects "major defections" from Lazio among Conservatives as in the GOP.
Just as stridently, Lazio spokesman Barney Keller shot back: "Desperate candidates often say foolish and ridiculous things. It's over for Steve Levy. Over."
Both statements run the risk of being quite overblown. But they show how dramatically the cracks in that ever-changing R-C relationship are now widening.