Two billionaires in New York City will try to hold sway in the U.S. Senate race in Indiana.

Mayor Michael Bloomberg has planned a fundraising party tonight at his home for Sen. Richard Lugar, R-Ind.

Steve Forbes, a former presidential contender, will headline a fundraiser Tuesday at a private club in New York for Lugar’s opponent in the 2012 Republican primary election, state Treasurer Richard Mourdock.

Bloomberg and Forbes made their fortunes in publishing. Mourdock’s campaign pointed out that Bloomberg is a former Republican who became an independent.

“I am a little shocked but not completely surprised to learn that Senator Dick Lugar is yet again soliciting assistance from another liberal politician in an effort to fill his campaign coffers,” Mourdock said recently on his website.

Mourdock campaign spokesman Christopher Conner lumped Bloomberg in with “left-leaning” Republicans who are supporting Lugar, including Sens. Lisa Murkowski of Alaska and Susan Collins of Maine, and ex-Rep. Mike Castle of Delaware.

David Willkie, Lugar’s political director, said in an email, “Mourdock is trying to draw attention away from his anemic fundraising and campaign.”

Willkie also noted that Mourdock had been endorsed by Herman Cain, who suspended his GOP presidential campaign Saturday after allegations of sexual harassment and an accusation that he had had a 13-year extramarital affair.