For the first time, Illinois senators on Tuesday heard FBI recordings that allegedly show Gov. Rod Blagojevich shaking down a businessman for campaign contributions. 

The prosecution played four tapes at the governor's impeachment trial in Springfield, Ill. The conversations were recorded in early December and revolved around an apparent attempt to extract donations from the Illinois horse-racing industry in exchange for the governor's signature on a bill that would give a portion of state casino revenues to the industry. 

In one of the conversations, lobbyist Lon Monk is heard telling Blagojevich to call John Johnston, the head of a local racetrack. "It's better if you do it from a pressure point of view," Monk says. 

"I'm telling you he's gonna be good for it," the lobbyist says. 

In a prior phone call, Blagojevich's brother Rob -- who headed his campaign fund -- relays a conversation in which Johnston supposedly says, "I'm good for it. ... I gotta just decide what, what uh, accounts to get it out of." 

The conversations are not explicit, and do not address the most egregious offenses detailed in the FBI's lengthy affidavit against Blagojevich. 

But the U.S. attorney won't release most of the tapes because that might interfere with his criminal investigation. 

Illinois Rep. Jack Franks told FOX News earlier Tuesday that once senators hear the tapes, "It's over." 

He said House prosecutors read transcripts of the four calls to members of the special impeachment committee on which he sits over the weekend. 

As the impeachment trial got underway Tuesday, Blagojevich continued to maintain his innocence in a rapid-fire series of media interviews. Blagojevich, who is boycotting the proceedings, told FOXNews.com's Strategy Room that he refuses to resign, in part because he doesn't want his children to think that "their dad did something wrong."  

"I haven't done anything wrong. I haven't committed any crimes," he said. "They're trying to run me out of town." 

Back in Springfield, Ill., FBI agent Daniel Cain also vouched for the accuracy of quotes contained in criminal charges filed against Blagojevich, as part of the impeachment trial. Cain testified that those involved in the federal investigation were very careful to identify Blagojevich's voice when they eavesdropped on conversations. 

House prosecutor David Ellis walked Cain through each quote filed as part of the criminal charges against Blagojevich, and Cain confirmed that each part of the affidavit was accurate. 

Blagojevich told FOXNews.com that he might have toned down the language of some of those quotes had he known his conversations were being recorded. 

"If I'd have known people were listening, some of the expletive-deleteds would have been expletive-deleteds," he said. 

In an interview with FOX News earlier Tuesday, he brushed off the idea that he could still bargain for a severance package if he stepped down immediately. 

"I heard of no such thing. I'm not interested in resigning. I've done nothing wrong," Blagojevich told FOX News. 

Illinois' state government is immersed in the impeachment proceedings, raising questions about how much state business is getting done as the Senate trial unfolds. But Blagojevich has repeatedly said he will not resign and that he has done nothing wrong. 

Blagojevich was allegedly caught on tape by the FBI discussing how to sell off President Obama's former Senate seat, shake down a children's hospital and get members of the Chicago Tribune editorial board fired. 

Blagojevich told FOX News Tuesday that anything caught on tape was probably taken out of context. 

"When the full story is told, the full story shows an effort by the governor to make a decision that is right for the people of Illinois," Blagojevich said. "It is fundamentally wrong and unfair to take little pieces of conversation and not tell the whole story." 

Blagojevich chalked up some of the furor to "rough-and-tumble" politics in Illinois. 

"This is a tough business and I'm not the only politician in America who's scrutinized," he said. 

Click here to read the transcript of the FBI tapes played at Tuesday's trial. 

FOX News' Steve Brown and The Associated Press contributed to this report.