Poizner said at a press conference that Whitman campaign strategist Mike Murphy issued "crystal-clear" threats to his staff in an attempt to effectively "cancel the election" by pushing him to drop out of the race.
"This is not an attempt to be hardball and to be aggressive, but this is an attempt to effectively manipulate the election process, the integrity of the election process, by issuing these threats behind the scenes to get me not to run," he said.
The campaign provided a copy of an e-mail in which Murphy asks an unidentified Poizner campaign consultant if there is any chance Poizner, who is trailing Whitman in the polls and in campaign funds, will reconsider his run.
The e-mail, provided by the campaign to reporters and in a letter to law enforcement officials, says the Whitman camp can spend $40 million "tearing up Steve if we must."
"I hate the idea of us each spending $20 million beating on the other in the primary, only to have a damaged nominee," Murphy wrote, according to the e-mail.
In the e-mail, Murphy offers that the campaign could "unite the entire party behind Steve right now to build a serious race" for U.S. Senate in 2012.
In a letter sent to the FBI, U.S. Attorneys Office, Fair Political Practices Commission and state Attorney General Jerry Brown, Poizner also claims Murphy told a senior adviser that the campaign would "put (Poizner) through the wood chipper" if he did not drop out of the race.
In a statement issued this afternoon Murphy acknowledged that he had spoken to Poizner consultants about the viability of the insurance commissioner's gubernatorial bid, but charactarized the accusations made as "ridiculous charges."
"[A]ll I can say is that I'm starting to worry about Commissioner's mental condition," he said in the statement, adding: "Hopefully the Commissioner was not serious about wasting taxpayer dollars by asking state and federal authorities to waste their time on such a silly matter of perfectly legal politics."
Poizner said he "absolutely, positively" plans to remain in the race.
"Maybe these kinds of threats, maybe that works on some people, unfortunately, but it won't work on me," he said.
Click here to read Poizner's letter.
*This post was updated at 1:24 p.m. with Murhy's response.
VIDEO: Steve Poizner holds a news conference this morning where he said a Whitman campaign official issued threats to his staff. Credit: Hector Amezcua/Sacramento Bee.