New York State Senator Ruben Diaz Sr. alleges that New York City Mayor Michael Bloomberg secured the passage of a gay marriage bill with the purchase of four GOP votes.

Bloomberg, a Republican turned independent, made out checks of $10,300 – the maximum allowed – to the reelection campaigns of Republican Senators Mark Grisanti of Buffalo, James Alesi of Rochester, Roy McDonald of Saratoga and Stephen Saland of Poughkeepsie.

The four senators last month provided the GOP support needed for marriage equality to pass in the Empire State.

Grisanti, considered the most vulnerable of the four Republicans, received another $40,000 in donations from people who publicly back gay marriage rights, including $10,000 from gay philanthropist Tim Gill.

Diaz, the only Democrat in the chamber to vote against the measure, suggested the men had been bribed.

“It appears that State Senators Stephen Saland, Mark Grisanti, James Alesi and Roy McDonald sold their votes to the Mayor of New York City Michael Bloomberg for $10,300 each,” Diaz wrote Thursday in a post at his website.

Diaz, who is also a Pentecostal minister, called on Attorney General Eric Schneiderman and the media to look into people “buying and selling votes.”

“So I wonder if these rumors and accusations are reason enough for the Attorney General to start an investigation and for the editorial boards to have the integrity to declare that the Senate in Albany is still corrupt.”

Last week, Diaz invited Bishop Timothy Dolan to join him in demonstrating against the law on the first day it takes effect.

(Related: NOM pledges to raise $20 million to fight marriage equality.)