Arguing that California's newly drawn Senate districts are unconstitutional, a Republican Party-backed group filed a lawsuit Thursday asking the California Supreme Court to kill the new maps.

"We believe there are serious constitutional flaws in the maps produced by the redistricting commission, and these are matters that the Supreme Court should look at immediately," said David Gilliard, a Sacramento-based GOP political consultant leading the effort.

Gilliard said his group, Fairness & Accountability In Redistricting), also has collected about 100,000 signatures in a referendum drive aimed at asking voters to reject the newly drawn Senate districts.

If the group can collect 504,760 valid signatures by Nov. 14, the state Senate lines will be put on hold until the referendum is held in the June 2012 election.

California's 40 state Senate, 80 Assembly and 53 congressional districts were drawn for the first time this year by a 14-member independent panel, the California Citizens Redistricting Commission, rather than by the Legislature.

Gilliard's group has raised nearly $500,000 thus far for its two-pronged effort to kill the Senate maps, including $188,000 from the California Republican Party and a cumulative $200,000 from current or past GOP state senators.

The donors include U.S. Rep. Jeff Denham, R-Atwater, whose $25,000 contribution made him the first member of Congress to put money behind the challenge.

Denham, a former state senator, made the $25,000 contribution to FAIR on Tuesday using funds he originally raised for a lieutenant governor's race, records show.

Many political analysts have said the new districts give Democrats a strong chance of gaining two additional seats in the Senate, enough to gain the two-thirds supermajority needed to raise taxes or fees.

Gilliard, in a written statement, said the new boundary lines dilute Latino voting clout in parts of the state and violate criteria established by voters in a 2008 ballot measure that created the redistricting commission.

The redistricting commission, through spokesman Rob Wilcox, said that members are "confident that its final district maps will withstand any and all legal challenges … . The commission followed the U.S. and California constitutions in drawing the district maps in an open and transparent process."

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