Manhattan Borough President Scott Stringer endorsed Sen. Kirsten Gillibrand (D-N.Y.) on Monday, months after mulling a possible primary challenge to her.

Stringer was one of a number of progressive New York Democrats who expressed interest in taking on Gillibrand, appointed to the Senate post in January, in a 2010 primary. He even went so far as to open an exploratory committee, only to drop his plans in May, in part, he said, because of the White House’s efforts to avoid a Democratic primary.

He did not mention Gillibrand in a statement announcing his decision, but did indirectly criticize some of the moderate positions she had espoused in the House. “I firmly believe that innovative thinking on issues like education and the urban environment must be joined with bedrock Democratic values on gun control and immigration if New York’s interests are to be effectively represented in Washington,” he said.

Fast forward to December, when Stringer seems to be feeling a lot better about Gillibrand’s record.