In letter to Sen. Roy McDonald, Gov. Andrew Cuomo said that if the Republican lawmaker were to continue his campaign on the Independence Party line he would have his “full endorsement.”

“If you decide to go forward with your campaign you will have my full endorsement,” Cuomo wrote in the letter distributed by his office this afternoon.

McDonald is one of the four Republicans to back Cuomo’s same-sex marraige law in June 2011. The support from the GOP lawmakers was essential for the measure to pass.

“It is now evident that you paid a political price for your convictions,” Cuomo wrote in the letter. “You should not be left to stand alone now.”

Cuomo doesn’t elaborate on whether he would provide financial support or appear with him in campaign events.

The Democratic governor had hinted in recent days that he was considering the endorsement of the lawmakers, including Sens. Mark Grisanti and Stephen Saland. He told reporters on Tuesday he was “elated” by the news of Salands victory, but remained concerned about McDonald’s chances.

Earlier Cuomo had gone further, saying he hoped both were re-elected.

Grisanti easily won his primary, while Saland was able to win a narrow victory over Republican Neil Di Carlo, who retains the Conservative Party line.

The development comes as McDonald is considering whether to continue on in the race after losing the Republican Party ballot line to Saratoga County Clerk Kathy Marchione.

It also comes after McDonald faces pressure from Republicans to drop out of the race.

Should McDonald continue on, Democrats had seen an opening with the chance of a split conservative-Republican electorate. Claverack town Supervisor Robin Andrews, who is openly gay, is running on the Democratic line.

Cuomo’s endorsement has the potential to further alienate him from the Senate Democratic conference, already smarting after he signed off on a redistricting plan for state legislative districts drawn by majority lawmakers in the Assembly Senate.

Republicans, meanwhile, would certainly not want McDonald to continue on in the race in a split contest, possibly forcing them to divert resources.

The Senate is divided 33-29 in favor of the Republicans.

But Cuomo’s letter also coincides with a renewed push from same-sex marriage advocates and groups who had hoped McDonald would stay in the race. Empire State Pride Agenda Executive Director Lynn Faria said in a phone interview Tuesday that her group would continue to provide monetary and boots-on-the-ground support for McDonald if he continues.

Some of the groups are gearing up for the legalization of gay marriage in other states and a McDonald victory would bolster their argument for other state lawmakers and officials to make a similarly tough vote.

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