Faced with a petition drive to oust Gov. Gray Davis (search) that has netted twice the necessary signatures, supporters of the embattled executive are mulling a legal challenge, saying they have discovered widespread illegalities in the recall effort.

Lawyers for Taxpayers Against the Governor's Recall (search) said they planned to file a lawsuit Tuesday to seek an injunction against the Republican-led process.

The pro-Davis group said the alleged improprieties included the use of signature gatherers who were not California residents and not registered to vote in the state. They also said at least two signature circulators were convicted felons.

"We believe that just as it is incredibly important in this kind of process that voters knowledgeably sign or don't sign petitions, it is also incredibly important that the circulators who are circulating those petitions do so in a legal fashion abiding by the law," said Steve Smith, campaign manager the group. "That did not happen in this case."

The development came on the same day organizers of the recall drive turned in their last batch of petitions, saying they had collected 1.6 million signatures to get a recall on the ballot - almost double what they needed. Counties still must verify the signatures as valid.

Chris Wysocki, a spokesman for Rescue California Recall Gray Davis (search), said the signatures were carefully monitored and predicted any lawsuit challenging the recall would quickly be tossed out.

"We had to make sure that we played this strictly by the numbers and by the book and we did everything possible," Wysocki added. "A signature-gatherer did not get paid unless they were a registered voter."

Even Davis supporters concede that a recall election looks nearly inevitable. Legal battles, however, could delay it from this fall to March, when heavy Democratic turnout for the state's presidential primary could help Davis.

The recall effort has been fueled by discontent over California's energy crisis and $38 billion budget deficit, sending Davis' approval ratings to record lows.

Officials with the secretary of state's office, which is responsible for determining if the recall should proceed, have said signatures should be considered valid even if the circulator was not a registered voter or had other legal problems.

"I will continue to provide guidance based on the law, not the interests of one side or the other," Secretary of State Kevin Shelley (search), a Democrat, said in a statement Monday.

The lieutenant governor will set the election date after the secretary of state certifies sufficient signatures have been turned in. Recall backers hope that will happen next Wednesday, when counties face a deadline to report signature counts to the secretary of state.

A recall ballot would have two sections: in the first, voters would be asked whether or not to oust Davis, and in the second they would choose from a list of candidates to replace him. Davis' name would not be on that list.

So far the only declared major party candidate is Rep. Darrell Issa (search), a Republican who has spent $1.5 million of his own money to fund the recall.

The state's major Democratic officeholders have said they do not intend to put their names on the ballot. Strategists from both parties believe Davis would be more likely to survive if there are no Democratic alternatives.