JEFFERSON CITY, Mo. (AP) — A proposed ballot initiative aims to replace Missouri's system for drawing state legislative districts with a model designed to have the number of seats won by each party more closely reflect its statewide vote.

If election officials validate enough signatures collected by Clean Missouri, the group sponsoring the proposal, voters will have the final say Nov. 6.

The stakes are high: Another round of redistricting begins after the 2020 census.

More than $2 million has flowed into Clean Missouri's coffers, including at least a quarter-of-a-million dollars that originated from the lobbying arm of billionaire George Soros' philanthropic network. Soros' financial support of liberal and progressive causes around the country has made him a frequent target of conservatives.

That, and support from groups representing labor, teachers, abortion-rights and other left-leaning causes has led some Republicans to cast Clean Missouri as a partisan effort to help Democrats gain ground against GOP supermajorities in the House and Senate.

Clean Missouri advocates point to support they've received from Republicans, like former U.S. Sen. Jack Danforth and state Sen. Rob Schaaf, and argue that their plan would increase competitiveness in elections and lead to a General Assembly more representative of voters' wishes.

A group called Advance Missouri formed in February in Kansas City to weigh possible legal challenges against Clean Missouri and has reported receiving more than $60,000 worth of contributions. Most of that has come from a Virginia-based organization called Fair Lines America Inc., which has spent money in Michigan to block a similar initiative.

Under the current system, two governor-appointed bipartisan committees draw legislative districts that are compact, contiguous and filled with roughly the same number of people.

Clean Missouri's plan would diminish the role of those committees and invest new power in the state auditor and a newly created non-partisan state demographer, who would be charged with also maximizing "partisan fairness" and competitiveness.

That would be done using a formula that tests for partisan gerrymandering to curb the practice of spreading voters favoring one party throughout districts that overwhelmingly favor the other, which diminishes their impact, or packing voters into a handful of districts to similarly reduce their impact.

"Not every place, everywhere, can have a competitive election," said Clean Missouri's campaign director Sean Nicholson. "But there's going to be a whole lot more competition, and there's going to be a lot fewer places where everything is just decided before candidates run."

Former Republican Rep. Justin Alferman, the state GOP's point person for the last round of redistricting, rejected the idea that the demographer could base decisions solely on data.

"I think it's an absurd argument that someone can come in with an objective mind, that doesn't have a political slant," he said.

Republican State Leadership Committee President Matt Walter agreed. He said the idea that a party's proportion of seats in the Legislature should match the proportion of votes it won statewide was "nonsense."

"Republicans are at all-time historic highs because they have run better candidates," Walter said.

In 2016 Republicans captured about six additional seats in Missouri beyond what would have been expected by their vote share, according to an analysis by The Associated Press. Some analysts say Republicans' advantage in the state may be higher.

Clean Missouri's measure would also ban most lobbyist gifts, among other proposals. A spokeswoman for the Secretary of State's office said election officials would likely need until the Aug. 14 deadline to evaluate the submitted signatures.