Billionaire Michael Bloomberg has thrown his weight behind Pennsylvania Republican Senate candidate Pat Toomey less than a week after he took the stage at the Democratic National Convention to boost Hillary Clinton.

The former New York City mayor announced through his Super PAC that he will support incumbent Toomey in his Pennsylvania Senate battle with Democrat Katie McGinty.

Bloomberg’s support for Toomey is rooted in the work he has done in Congress to bridge the gap between Democrats and Republicans on gun control ever since the tragic school shooting in Newtown, Connecticut, in 2012.

"In the wake of Newtown, Pat Toomey crossed party lines to lead the fight to reduce gun violence in America by co-sponsoring legislation to close the background check loophole," Bloomberg said."His pragmatic leadership in Washington deserves the support of every Pennsylvanian."

Toomey said he is "pleased to receive Mayor Bloomberg’s support."

"I am proud of my work to keep guns away from those who have no right to them–criminals, terrorists, and those with severe mental illness, and I am pleased to receive Mayor Bloomberg’s support," Toomey said. "It’s only through finding common ground across party lines that we will make progress on this and other critical issues."

Toomey has long received support and praise from Bloomberg-backed gun control groups. Mayors Against Illegal Guns spent six figures on television ads in Pennsylvania in 2013 that said Toomey embodies "courage and common sense." Everytown for Gun Safety, another Bloomberg group, said in 2015 that it "is grateful for all the leadership Toomey has shown in working to reduce the country’s epidemic of gun violence."

The endorsement has put the McGinty campaign on defense.

"Pat Toomey is not a moderate on gun safety, and he’s certainly not a pragmatic leader," Sean Coit, the McGinty campaign’s communications director, said in an email. "Just two weeks ago, Pat Toomey bragged to Pennsylvanians about his A rating from the gun lobby, and in June, he voted against blocking terrorists from buying guns."

"No endorsement is going to change the fact that Pat Toomey is in lock step with the gun lobby in Congress," Coit said.

Pressed on whether the McGinty campaign courted Bloomberg for his endorsement, Coit said that "Katie hasn’t been shy about her views on commonsense gun safety."

Bloomberg said in a statement that his decision to endorse Toomey aligns perfectly with his speech at the Democratic convention last week.

"As I said when I appealed to Republicans and Independents from the stage of the Democratic National Convention in Pennsylvania last week, I look at the candidate, not the party label, because we can only solve our biggest problems if we come together across party lines," Bloomberg said.

Bloomberg’s Independence USA Super PAC has not yet spent any money during the 2016 election, but if past elections are any indicator, it will be a presence. The group spent over $8 million in 2012 and just under $6 million in 2014, according to the Center for Responsive Politics.

A spokesman for Independence USA did not respond to follow-up questions on the endorsement.

It is unclear whether Bloomberg saw McGinty’s speech at the DNC last week, which many observers said was a failure.