Chicago ? Illinois Senate candidate Jack Ryan dropped out of the race Friday amid a furor over lurid sex club allegations that horrified fellow Republicans and caused his once-promising candidacy to implode in four short days.

“It’s clear to me that a vigorous debate on the issues most likely could not take place if I remain in the race,” Ryan, 44, said in a statement. “What would take place, rather, is a brutal, scorched-earth campaign — the kind of campaign that has turned off so many voters, the kind of politics I refuse to play.”

The campaign began to come apart Monday after the release of embarrassing records from Ryan’s divorce. In those records, his ex-wife, “Boston Public” actress Jeri Ryan, said Ryan took her to kinky sex clubs in Paris, New York and New Orleans and tried to get her to perform sex acts with him while others watched.

Ryan disputed the allegations, saying he and his wife went to one “avant-garde” club in Paris and left because they felt uncomfortable.

In quitting the race, Ryan lashed out at the media and said it was “truly outrageous” that the Chicago Tribune got a judge to unseal the records.

Top Illinois Republicans immediately began the work of selecting a new candidate. Their choice will become an instant underdog against Democratic state Sen. Barack Obama in the campaign for the seat of retiring GOP Sen. Peter Fitzgerald. Obama held a wide lead even before the scandal broke.

“I feel for him actually,” Obama said on WLS-AM. “What he’s gone through over the last three days I think is something you wouldn’t wish on anybody. Unfortunately, I think our politics has gotten so personalized and cutthroat that it’s very difficult for people to want to get in the business.”