Arizona has long been held up as a model of how to create fair, representative electoral maps largely free from partisan bias.

But a Republican proposal to overhaul the independent commission that draws the state’s maps threatens that reputation.

The measure, which is sponsored by GOP leadership in both houses of the legislature, was approved on party lines by a Senate committee last week. If it passes the Republican-controlled legislature, it would go before voters as a ballot initiative in November.

A wide range of Arizona political observers tell TPM that the legislation would give lawmakers more influence over redistricting, making it easier for them to draw lines that boost their party.

“This is obviously a Republican play to increase their control over the redistricting process during the next go-around [of map drawing],” said Chris Herstam, a former Republican majority whip in the Arizona House of Representatives, who helped establish the state’s independent commission in 2001. “To me, it’s very partisan.”

The move in Arizona comes at a pivotal moment in the redistricting wars. Ahead of the 2020 census, which is followed by a once-a-decade redistricting process, Democrats have launched an unprecedented national push to create fairer maps across the country. But Republicans in many states are doing their utmost to maintain the partisan system that last time allowed them to carry out extreme gerrymanders in numerous large states, giving their party a crucial edge in elections throughout the decade.

They’ve fought doggedly to keep maps in Texas, North Carolina, and Wisconsin that courts have found to be gerrymanders. And in Pennsylvania, some prominent Republicans have even threatened to impeach several of the state’s Supreme Court justices for approving a congressional map intended to fix aggressive GOP gerrymandering.

“As other states are facing legal challenges to their maps or through ballot measures are trying to move to a more independent process, it would be a step backwards for us,” Joel Edman, the director of the Arizona Advocacy Network Executive Director, told TPM of the proposed ballot initiative. “Which would be a real shame, because we were one of the first states to create an independent process.”

National Democrats, too, are alarmed.

“The proposal introduced by Republicans in the state legislature would unnecessarily politicize the current system and undermine the will of the voters,” Kelly Ward, the executive director of the National Democratic Redistricting Committee, said in a statement. “Their draft language would make it more difficult to ensure a fair map-drawing process and allow the legislature to sidestep the independent commission’s work on a whim.”

Ward added that if the measure makes it onto the ballot, her group plans to “invest resources to expose this partisan power grab.”

Back in 2001, a voter-approved amendment to Arizona’s constitution established an independent commission to oversee drawing state legislative and congressional districts. Four commissioners — two Democrats and two Republicans — are selected by party leaders from a pool of people that are vetted and chosen by the commission that oversees appellate court appointments. The fifth, who serves as the chair, is an independent selected by the partisan commissioners.

The integral role of the appellate court in selecting candidates serves as a “buffer,” Edman said, that allows the commission “to be removed from politics and removed from the politicians at the Capitol.”

The system appears to have been successful. In drawing districts, the commission prioritizes geographical cohesion, competitiveness, and the need to fairly represent minority voters. It makes little effort to preserve the districts of current incumbents — something that lawmakers themselves tend to focus on when they control the process.

In 2016, Republicans won five out of the state’s nine congressional seats, while Donald Trump beat Hillary Clinton by 3.5 percentage points.

Mark Gersh, who has worked with Democrats on redistricting, called Arizona a “gold standard for redistricting” that fairly represents a state home to many independents and a large and growing Latino population.

“You’ve actually got everything you want,” Gersh said. “You have competitive races and you have ones that respect minority votes.”

Indeed, Arizona was one of 15 states to get a perfect score on a set of tests run by a Princeton University gerrymandering project, which aims to identify partisan gerrymanders.

Under the proposal being pushed by Senate President Steve Yarbrough and House Speaker J.D. Mesnard, party leaders would handpick the commissioners without vetting by the appellate court commission. The proposal also would expand the number of commissioners to eight — three Democrats, three Republicans, and two independents.

“The Arizona Independent Redistricting Commission has now redrawn our congressional and legislative districts twice, and both times the process was anything but independent or apolitical,” Mesnard told TPM in an emailed statement. “Arizona voters deserve an opportunity to weigh in on improvements to the process, like increasing the number of independents on the commission to better reflect the state’s party registration, diversifying the geographic representation of the state, and requiring that the population of districts be more evenly divided. These changes would ensure equality, as well as independence.”

Herstam, the Republican who helped establish the original independent commission, said that the expansion is instead intended to give the GOP more sway over how districts are crafted.

“It’s a play by the Republicans to give them more of an opportunity to get people of their ideology on the commission, even if they have ‘independent’ by their name,” Hestram said.

Democratic redistricting experts point to the GOP’s long history of attempting to undermine the independent commission. Most recently, the legislature brought a case claiming that it’s unconstitutional to cut lawmakers out of the redistricting process. The Supreme Court rejected that challenge in 2015. The following year, it rejected a separate challenge brought by Republicans that claimed the state’s map was overly favorable to Democrats.

During a Wednesday night caucus discussion, Yarbrough proposed adding a ninth commissioner who could break potential four-four partisan gridlock and would be chosen by the appellate court. The move seemed to be a concession to critics of the plan.

State Sen. Juan Mendez, one of the Democrats who voted against the original proposal, told TPM that the tweak wasn’t enough.

“In his testimony to the committee, [Yarbrough] dismissed the idea that there could be an independent who is not actually a partisan person who is just pretending to be independent,” Mendez said.

“It looks to me like he’s just throwing darts at the dartboard to see what sticks,” Mendez continued. “He’s trying to shore up Republican support for it, but that’s definitely not how I’d like to see someone be tinkering with democracy.”

Yarbrough’s office did not respond to multiple requests for comment.

Mendez and Democratic redistricting experts expect the initiative to end up passing the legislature and appearing on the ballot in November. They hope that, with a competitive gubernatorial and Senate race, voters will turn out en masse to reject it. But they’re not taking it for granted.

“You never know what the rhetoric is going to be,” Gersh said. “There’s going to be some misinformation campaign that will say what’s wrong with” the current system.

“You never know how these things go,” Gersh added.