PHOENIX — A lawyer for the Republican-controlled Legislature asked a federal court Friday to void a decision by Arizona voters to have an independent commission decide how the state is divided into its nine congressional districts.

Peter Gentala acknowledged that voters, in approving Proposition 106 in 2000, said they no longer wanted politicians drawing the lines, a process that often resulted in legislative and congressional maps that favored incumbents and their political allies. That measure amended the Arizona Constitution to create the five-member Independent Redistricting Commission.

But Gentala told a three-judge panel that voters had exceeded their legal authority, at least as it applies to congressional districts. He said a provision in the U.S. Constitution specifies that the Legislature of each state determine the “time, place and manner” of elections.

But Judge Murray Snow said he’s not sure the provision about holding elections also governs the redistricting process.

“If you’re telling us the constitutional test says it, I want you to show me where,” he told Gentala. The attorney responded by arguing the word “manner” is broad enough to include redistricting.

Gentala said the supremacy of the U.S. Constitution trumps the power of Arizona voters to be the ultimate lawmakers.

But the real fight is about raw political power.

GOP lawmakers are hoping for a ruling in their favor — and quickly. They want to redraw the lines before this year’s election in a manner more favorable to Republicans than the current maps, which created a congressional delegation with five Democrats and four Republicans.

Mary O’Grady, who represents the redistricting commission, pointed out that the Legislature never challenged Proposition 106 when it was first approved — and when the congressional maps crafted by the commission a decade ago were more favorable to Republicans.

It was only when they did not like the most recent result that Republicans who control the Legislature raised the issue of their rights under the U.S. Constitution being ignored.

Nothing this three-judge panel rules would affect the other half of Proposition 106, empowering the commission to draw lines for the state’s 30 legislative districts.

But in a separate fight playing out in another federal courtroom, another group of Republicans is seeking to have that legislative map declared invalid.

They contend the commission ignored legal requirements for equal population of each district to instead create a map more favorable to Democrats.

A ruling for challengers in that case would simply force the commission to redraw the legislative maps. It would not return the power to the Legislature.

The outcome of the case heard Friday could turn on a simple question: Who is the “legislature?”

There is no dispute over the clause in the U.S. Constitution that says “the times, places and manner of holding elections for Senators and Representatives, shall be prescribed in each state by the legislature thereof.’’

Gentala said there can be only one meaning to that: the representative body elected by voters.

But O’Grady said the Arizona Constitution determines who has legislative authority. And in this case, she said, voters amended that document through Proposition 106 to say that legislative power to draw district lines would be given to this five-member commission.

That prompted Judge Mary Schroeder to ask, “How far can the state go in excluding the Legislature from the (redistricting) process?”

O’Grady responded that voters were free to exclude them entirely. But she also pointed out that if the Legislature is unhappy with the process, it is free to ask voters to repeal Prop. 106.

O’Grady also argued that the Legislature doesn’t have the legal right to be in court to challenge Proposition 106 in the first place.

She pointed out the Voter Protection Act, another section of the Arizona Constitution, forbids the Legislature from repealing or altering any measure approved by voters themselves.

Judge Paul Rosenblatt, who presided over the three-judge panel, promised a quick ruling.