SALT LAKE CITY — Proposition 4, the ballot initiative creating an independent redistricting commission as a stopgap against what's known as gerrymandering by lawmakers, won voter approval by less than 1 percentage point.

The proposition called Better Boundaries had 512,146 "For" votes compared to 505,144 against when counties reported their final canvasses Tuesday afternoon. The 7,002 vote-difference is a represents a 0.68 percentage point victory.

"This is an exciting day for Utah," the co-chairmen of the Proposition 4 campaign, former Salt Lake City Mayor Ralph Becker, a Democrat, and Republican Jeff Wright said in a statement.

The pair said they are confident that after the final canvass, the proposition will win "and the voice of the people will once again be heard in drawing legislative lines — making sure Utahns choose their representatives and not the other way around."

Becker and Wright thanked "the countless supporters and volunteers who came together in a truly bipartisan and grassroots effort for a cause that will improve accountability and transparency in our state."

They also said they "expect the voice of the people will be respected and honored."

The American Civil Liberties Union of Utah also joined in that call, urging lawmakers "to respect the will of 500,000 Utah voters and let the independent redistricting commission do its job."

Brittney Nystrom, the ACLU of Utah's executive director, said elected officials who benefit from gerrymandering "are naturally resistant to a more open and nonpartisan redistricting process."

The proposition put on the ballot by voters creates a seven-member commission appointed by elected officials from both parties to recommend boundary changes to reflect population changes in the once-a-decade census.

The next census will be in 2020 and redistricting will follow a year later.

The Utah Legislature still has the final say over boundaries for congressional, legislative and State School Board districts, but must vote the commission recommendations up or down.

That's seen as putting political pressure on the GOP-dominated Legislature, which has been accused in the past of gerrymandering — the manipulation of political boundaries to favor one party or candidate over another.

Proposition 4 also sets new requirements for lawmakers as they draw up their own redistricting plans, including having to minimize dividing up counties, cities and towns.

Among the biggest concerns raised about past redistricting efforts is the division of Salt Lake County into three of the state's four U.S. House districts in 2011, diluting the county's Democratic influence.

The Proposition 4 campaign, largely funded by out-of-state groups including the national ACLU, emphasized bipartisan support for the independent redistricting commission.

One of the group's TV commercials featured footage of a Republican icon, President Ronald Reagan, calling for an end to gerrymandering through establishing such commissions to oversee redistricting.

The chief opponents of Proposition 4, including outgoing Senate Majority Leader Ralph Okerlund, R-Monroe, have called it "a cleverly disguised partisan plan" to favor Democrats.