Washington (CNN) - Fresh on the heels of Joe Miller's surprising win over Sen. Lisa Murkowski in the Alaska Republican Senate primary, the Tea Party movement is setting its sights on Delaware.
Now the Delaware Republican Party is taking heed – and taking on – the Tea Party-backed candidate in the state's Republican Senate primary, sparking a war of words between the state's establishment GOP and the Tea Party movement.
It's a race that pits conservative Tea Party favorite Christine O'Donnell against moderate Rep. Mike Castle, Delaware's former two-term governor and lone Congressman since 1993.
Both candidates' campaigns have become increasingly caustic, especially as Tea Party-backed candidates across the country have picked up win after win against GOP establishment candidates.
The Tea Party Express endorsed the conservative O'Donnell in July, and recently committed to spending at least six-figures in the state.
"We are launching an aggressive multimedia and multi-platform campaign to help propel Christine O'Donnell to victory, and we've only just begun," Amy Kremer, Chairman of the Tea Party Express, said in a statement.
The group originally planned to spend about $250,000 on the race, but is now considering expanding their presence with TV and radio ad buys in Philadelphia, said Tea Party Express political director Joe Wierzbicki.
A similar last minute media blitz by the Tea Party Express is credited with propelling Miller – a formerly little known candidate – to victory over Murkowski, the Republican Party-backed incumbent.
The group launched a series of TV and radio ads Thursday that support O'Donnell, and rail against Castle as a liberal candidate who "just keeps supporting the failed policies of Nancy Pelosi and Harry Reid."
It's a move that has the Castle campaign fighting back.
"Out-of-state interest groups have threatened to spend half a million dollars to fund the disgusting tactics being used by the O'Donnell campaign to make accusations," said Castle campaign manager Mike Quaranta.
Meanwhile, the Castle campaign has launched therealchristine.com, a site devoted to aggregating negative news about O'Donnell.
Tom Ross, state committee chairman of the Delaware Republican Party, defended the negative nature of the site. "The stories might not be flattering, but they are factual. ...Sometimes it is necessary to make sure that the facts get out there," Ross said.
O'Donnell has faced criticism over her personal finance issues and leftover debt from previous, unsuccessful bids for a Delaware Senate seat. She has also been accused of misstating the results of her run against Joe Biden.
When asked to clarify her remarks in an interview Thursday with radio host Dan Gaffney of WGMD, O'Donnell seemed to grow increasingly frustrated, and ultimately blamed her statements on a grueling campaign schedule.
Ross, who is backing Castle, said that O'Donnell's history is troubling.
"This is a group and candidate that clearly seem to have a problem with facts. It is shocking that they would come in and support a candidate of Christine O'Donnell's ilk," he said.
"It is sad that the group didn't investigate the candidate that they're supporting… and surprising they would take their supporters' money that they donated and squander it in such a fashion," Ross said.
Ross also questioned whether O'Donnell is capable of pulling off an upset similar to Miller's win in Alaska.
"In Alaska, it was that Joe Miller is an Ivy League grad, a war hero, excellent standing in the community," Ross said. "Look at Christine O'Donnell. She has none of those attributes. She is career politician. She's run unsuccessfully for Senate three times."
Yet, Wierzbicki criticized Ross for dismissing O'Donnell, calling her a true conservative.
"[Ross] is everything that is wrong with the establishment of the Republican Party. He should be fired for serving to undermine a Republican candidate who stands on conservative principles. It's his job to advance all Republicans in the state of Delaware. Instead he has become a tool for those who wish to thwart the Republican Party platform and turn the GOP into a Democrat-lite outfit. We find him reprehensible and shameless," Wierzbicki said.
Republican Gov. Chris Christie of neighboring New Jersey endorsed Castle Thursday.
The winner will face Democrat Chris Coons in the race for Vice President Joe Biden's former seat.