PHOENIX - Members of the Citizens Clean Elections Commission asked the Arizona Supreme Court Wednesday to void a new state law that dramatically raises the limits on how much candidates can collect in campaign donations from individuals and political action committees.

The lawsuit contends legislators can amend the limits only with a three-fourths vote, and only if it advances the goal of the 1998 voter-approved optional system of public financing for candidates.

The law didn't get the super-majority. And attorneys for the commission and its allies say it actually undermines the Clean Elections Act because lawmakers did not also increase payments for those who choose public funding.

Challengers want to quash the law before the new limits kick in on Sept. 13 and candidates start soliciting donations.

But Rep. J.D. Mesnard, R-Chandler, said the lawsuit will fail. He said legislators are free to alter the campaign contribution limits because they never touched the Clean Elections funding.

Political contributors are now limited to giving a maximum of $440 to a legislative candidate and $912 to a candidate for statewide office. The new law boosts the total to as much as $4,000.

And the law also totally eliminates the cap on total contributions any legislative candidate can take from all political action committees, now at $14,688.

It also scraps the current $6,390 limit on what any one person or political action committee can give to all candidates each year.

But the amount of public money available to candidates who agree not to take private donations remains unaltered. For legislative contenders, that is $15,253 for a primary and $22,880 for the general election.

Daniel Ruiz II, the commission's acting director, said voters, in approving the 1998 law, sought some equity in funding by not only specifying funding limits for publicly financed candidates, but also reducing the caps for those running with private dollars by 20 percent.

"They were competitive numbers," Ruiz said. "You could run for office as a Clean Elections candidate and be competitive, and you could run for office as a traditional candidate and be competitive."

Ruiz said that means campaign finance limits are linked to the voter-approved Clean Elections Act, which invokes state Constitutional limits on their ability to make changes.

A three-fourths vote and simply boosting public funding would have avoided that problem, he said.

Mesnard said lawmakers needed to act, arguing the current campaign finance limits are unconstitutionally low.

Attorney General Tom Horne has made the same claim in his bid to escape charges that he violated finance laws - saying that Arizona's artificially low limits interfere with a candidate's First Amendment rights to wage an effective campaign.

Mesnard said the other reason for the big boost in contribution limits is campaign finance has changed radically since 1998.

He cited the 2010 Citizens United ruling by the U.S. Supreme Court that paved the way for businesses and others to conduct independent campaigns for or against candidates, outside the control of the people they claim they are trying to help. The result, Mesnard said, are outside groups spending hundreds of thousands of dollars trying to influence campaigns while the candidates themselves are stuck trying to raise a couple of hundred dollars at a time.

"It's an attempt to combat what's been the rise of independent expenditures after Citizens United, which is a decade after the voters of Arizona passed the Clean Elections law," he said. "So we're in a whole different ballgame here."

He also said there's an advantage to the public by funneling more money through candidates' own campaigns than through the independent committees: The source of all contributions to candidates must be reported several times during the campaign, something that does not apply to the outside groups.