“Matt Gaetz needs to resign,” Kinzinger tweeted Thursday night, linking to a Daily Beast article about allegations against Gaetz, the details of which CNN has not confirmed. The moderate Illinois Republican has been a frequent critic of his own party, especially its embrace of Donald Trump and the former President’s lies about election fraud. No charges have been brought against Gaetz, and he has denied all allegations against him. Staring down those allegations, the Florida Republican has been reaching for a familiar, in-your-face strategy perfected over the last four years by Trump, who fueled his unconventional rise.Hours after news of the investigation went public, he went on Fox News to deny any wrongdoing and claim he was the victim of an elaborate extortion scheme. Then he wrote an op-ed declaring he “absolutely” would not resign. Gaetz’s campaign sent out fundraising pleas blaming the media for trying to take him down.Few GOP allies are speaking out on his behalf, and most Republicans have been keeping quiet, as the federal investigation hangs over his head. Federal investigators are seeking to determine whether Gaetz was provided travel and women in exchange for political favors as part of a broader probe, people familiar with the investigation tell CNN.The investigation includes scrutiny of a trip to the Bahamas and whether women were paid to travel for sex with the Florida Republican congressman and others, a potential federal crime, according to the sources.CNN has previously reported that investigators also have been examining allegations that Gaetz had sex with an underage girl who was 17 at the time and with other women who were provided drugs and money in violation of sex trafficking and prostitution laws.Lawyers for Gaetz declined to comment.CBS News, which first reported on the trip to the Bahamas, was told by a spokeswoman: “Rep. Gaetz has never paid for sex, nor has he had sex with an underage girl. What began with blaring headlines about ‘sex trafficking’ has now turned into a general fishing exercise about vacations and consensual relationships with adults.”Investigators are considering Gaetz’s connections to several associates in Florida who may have benefited politically in return for providing the congressman with benefits including escorts, travel and campaign donations, according to the sources.The investigation includes allegations from witnesses and other evidence that Gaetz may have used cash and drugs in his dealings with young women, CNN previously reported.This story has been updated with additional background. Annie Grayer and Sunlen Serfaty contributed to this story.