Washington (CNN) - New York Mayor Michael Bloomberg is hosting a fundraiser at his home for Sen. Joe Manchin, D-West Virginia, later this month, a source familiar with the event confirms to CNN.
Bloomberg, because of his wealth, has become one of the most prominent backers of gun control. He has praised Manchin for his leadership since he co-sponsored a measure, ultimately defeated by the Senate in April, to expand background checks for purchases at gun shows and over the internet.
A group founded by Bloomberg, Mayors Against Illegal Guns, pushed senators to support the background checks expansion and has criticized those who voted against it. Last month Bloomberg wrote a letter to New York donors asking them not to support those Democratic senators, Alaska's Mark Begich, Arkansas' David Pryor, Montana's Max Baucus and North Dakota's Heidi Heitkamp, because they did not support the proposal.
Manchin, who had received the endorsement of the National Rifle Association when he ran for election in 2012, is now the focus of a NRA ad campaign criticizing his actions. Manchin recently launched a counter-offensive defending himself.
Tickets for the July 22nd fundraiser start at a $1,000 a person, the source confirmed.
BuzzFeed first reported news of the event.