Former New York City Mayor Michael Bloomberg endorsed conservative Pennsylvania Sen. Pat Toomey's re-election bid, just days after the billionaire stumped at the Democratic convention in Philadelphia.

Bloomberg urged Americans to vote for Clinton in the fall onstage in Philadelphia, but he said on Monday he wants Pennsylvanian voters to split their ticket for Toomey this fall.

"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 in a statement on Monday shared by Independence USA PAC.

"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. His pragmatic leadership in Washington deserves the support of every Pennsylvanian."

Bloomberg is a staunch gun control advocate who supported Toomey's Democratic opponent, Joe Sestak, in 2010. Bloomberg's support for Toomey may influence fence-sitting independent voters to pick the incumbent senator over Democratic challenger Katie McGinty in November.