NEW YORK, Jan 7 (Reuters) - Former New York City Mayor Michael Bloomberg has donated $2.5 million to a political action committee that aims to help U.S. Senate Democrats maintain their majority in next year's congressional elections, a Bloomberg aide said on Tuesday.
Bloomberg, an independent who stepped down last week after 12 years as New York mayor, gave the money to Senate Majority PAC, according to Howard Wolfson, a former deputy mayor.
The news was first reported by Politico, which said Bloomberg developed a close relationship with Harry Reid, the Senate Democratic leader, working on issues from Hurricane Sandy relief to gun safety.
Senate Majority PAC is a so-called super PAC, which raised $3 million as of July 15, according to Federal Election Commission filings. The group was formed in 2011 and worked to boost Senate Democratic candidates in the 2012 elections.
One of the world's richest men, Bloomberg was a longtime Democrat who became a Republican in 2001 to get on the ballot, and later dropped his party affiliation.
He helped found and finance gun control group Mayors Against Illegal Guns in 2006. The group merged last month with another group, Moms Demand Action for Gun Sense in America.
Bloomberg has said he will focus on his charitable foundation, Bloomberg Philanthropies, and remain active in public health, gun control and government innovation. (Reporting by Doina Chiacu, additional reporting by Edith Honan; Editing by Nick Zieminski)