The Tea Party Express fired back Friday after the Delaware Republican Party filed a complaint with the Federal Election Commission against the group, alleging illegal coordination with the Senate campaign of Christine O'Donnell.
O'Donnell is challenging Rep. Mike Castle (R-Del.) in the state's GOP Senate primary set for Tuesday.
"These are desperate and baseless charges," the group said in a statement. "The Tea Party Express makes all its own decisions regarding the candidates it supports and the campaign activities in which we engage. Tea Party Express has never campaigned for a candidate at that candidate's request, suggestion or direction — whether it is Christine O'Donnell or any other candidate."
The Tea Party Express has been running radio and TV ads supporting O'Donnell and the complaint alleges the group has coordinated with the O'Donnell campaign on its paid communications in violation of federal election law.
The complaint cites an appearance by O'Donnell at a Tea Party Express rally and a radiothon that the group is planning for the candidate. O'Donnell is expected to speak during that event as well.
The complaint also accuses the O'Donnell campaign of accepting contributions from the Tea Party Express in excess of legal limits.
The Tea Party Express forcefully denied the charges Friday and accused the Castle campaign of hiding behind the state GOP.
"Mike Castle has cast lone Republican votes for these hideous campaign finance laws that strip away the rights of citizens to engage in the political process to protect incumbents and establishment politicians," the group's statement continued. "We've obeyed Mike Caste's unconstitutional law — so we know this FEC complaint is going nowhere legally."
The state Republican Party did ask the FEC to expedite the case. An FEC spokesperson suggested action on the matter before Tuesday's primary "would be a very quick turnaround."