The donation is set to be revealed in financial filings. | AP Photos Source: Bloomberg helped Graham

Former New York City Mayor Michael Bloomberg gave $250,000 to the super PAC supporting Sen. Lindsey Graham, (R-S.C.) in the primary battle he won by a wide margin last month, a source familiar with the donation told POLITICO.

The donation is set to be revealed in financial filings made public Tuesday by the West Main Street Values PAC, the source said.


The donation is the second Bloomberg has made in recent months to a Republican incumbent facing tea party unrest. Last month, filings showed that Bloomberg donated $250,000 to a super PAC supporting Sen. Thad Cochran (R-Miss.) in the rancorous primary with state Sen. Chris McDaniel.

The Graham super PAC was established by his allies, including former South Carolina State GOP chairman Katon Dawson.

Bloomberg’s goal in backing the GOP incumbents has been to support “candidates in primaries who have a track record of working across party lines,” said the source.

Unlike Cochran, whose narrow victory in the primary runoff has been questioned by McDaniel supporters, Graham won his race handily, but not easily.

Graham, who had incurred anger from the right in part for backing immigration reform, had a focused, early effort to stave off challengers. He ended up beating a divided field of six opponents, but none ever was able to gain traction in either voter support or fundraising.