Joe Mesi, the former heavyweight boxer appointed to a controversial new office in Buffalo by State Senate Democrats, resigned Thursday effective immediately.

Mesi, 35, who lost a contentious State Senate race last year to Republican Michael H. Ranzenhofer, is an apparent casualty of the State Senate coup orchestrated by an ally, former Erie County Democratic Chairman G. Steven Pigeon, and Buffalo Sabres owner B. Thomas Golisano.

In a statement, Mesi hinged his decision on “the events in Albany and the uncertainty over when or how the turmoil will end.”

“I accepted this appointment with the best of intentions and I’m very disappointed that events in Albany have undermined our ability to move forward with a positive agenda for Buffalo and Western New York.

“As a professional fighter, I worked hard to promote our community, whether inside the ring or through my community and charitable endeavors. . . . I want all my fans and friends to know that Joe Mesi never quit as a fighter and I will be back to serve my community in the future.”

Pigeon and his Responsible New York political fund, bankrolled by Golisano, loomed as major backers of Mesi during the campaign last year.

And Mesi is generally viewed as having been supported by Pigeon for the Senate post.

But now Pigeon is on the outs with Senate Democrats after he and Golisano engineered the June 8 coup that displaced the Senate’s Democratic majority.

Pigeon, who has remained at the center of Albany negotiations aimed at breaking the 31-31 gridlock resulting from the coup, said late Thursday the move was “clearly retribution” for his role in the upheaval.

“They’re just proving themselves as the petty and small-minded politicians they are,” he said, “and that’s why they’re doing something like this.”

He added that no deal to share power in the gridlocked Senate has been reached because Sen. Malcolm A. Smith of Queens, ousted as majority leader on June 8, has created so many patronage jobs at state offices in New York City.

“They refuse to do it because of the hordes of people Malcolm Smith has put on the payroll at 250 Broadway in New York City,” Pigeon said.

Austin Shafran, spokesman for the Senate Democrats, was unavailable to comment late Thursday.

Mesi was one of four local men hired in a new office established earlier this year by Senate Democrats when they held the majority. State records showed him making $70,000 per yer.