Former California Gov. Arnold Schwarzenegger is a master at marketing, having scaled to the top of three different professions.

But these days, the former bodybuilder and movie star is taking on perhaps his biggest sales challenge since he made “Last Action Hero”: He’s trying to get people to care about redistricting, the critical but arcane process of drawing political districts.

How those boundaries are drawn, block by block, once every decade, can determine which party controls the state legislatures and Congress. In many states, the process is overseen by a few politicians or whichever party dominates the legislature. That often leads to gerrymandering — districts created to favor a single party.

This distortion perpetuates a system in which 98 percent of House members are regularly re-elected in politically safe districts and is a big reason gridlock continues in Washington: The same players return year after year with no real fear of competition at home.

That lack of competition, Schwarzenegger said, has made voters think the system is rigged. And that frustration, he said, led many to vote for President Trump.

“People elected an outsider because of frustration,” Schwarzenegger said. “That’s one way of reaction. The other way is to fix the system.”

The 70-year-old is at the forefront of a push to change that system.

Challenges to existing redistricting systems are moving through courts in several states, with a pivotal case scheduled to be heard by the Supreme Court next month. Former President Barack Obama said overhauling redistricting will be one of his post-presidency priorities. This month, the National Democratic Redistricting Committee, fronted by former Obama Attorney General Eric Holder and others, will ramp up its operations, focusing on changing redistricting procedures in several states, either through the ballot box or court challenges.

But Schwarzenegger could be the movement’s most influential voice.

“Nobody is probably going to change their opinion about redistricting because President Obama and Eric Holder talk about it,” said Eric Rauchway, a professor of history at UC Davis. “They might if Schwarzenegger does. He has his own platform. He’s a celebrity. And he’s a moderate Republican.”

Plus, Schwarzenegger has redistricting street cred. In 2008, he led the passage of Proposition 11 that set up a nonpartisan citizens commission to draw the boundaries for California’s legislative seats. Two years later, voters approved a measure that enabled the commission to draw the lines for California’s congressional districts as well.

The key to talking about redistricting and gerrymandering, Schwarzenegger said, is to keep it simple.

“The mistake that a lot of people make is to talk about the details,” Schwarzenegger said during a recent phone interview. “Don’t start with the details, because then people see the pine needles but not the forest.”

The twist: If the Republican Schwarzenegger and his allies across the political spectrum, including Obama, Holder and Common Cause, are successful in taking the redistricting out of the hands of partisan officials, “there’s every reason to believe that Democrats would benefit from a more neutral” way of drawing the lines, Rauchway said.

But Schwarzenegger, who has tried to cultivate a “post-partisan” image since leaving office in 2011, disagreed that improving redistricting is designed to create a partisan outcome.

“It’s an issue where there should be no advantage or disadvantage to any party,” Schwarzenegger said. “It is meant to be an advantage for the people.”

And that’s why he’s directing his pitch at the mass market.

He’s been crafting his antigerrymandering campaign just as he would one of his action movies. He’s created a villain (Congress, entrenched politicians in general). He’s come up with a couple of memorable one-liners about his enemy — “(Congress) couldn’t even beat herpes in the polls.” And he explains the path to a happy ending: “Gerrymandering must be destroyed. You must demand gerrymandering reform in all 50 states.”

Instead of dropping in on late-night talk shows to promote his new project, Schwarzenegger is drawing a mass audience to the issue by starring in a series of short, funny videos, heavily salted with quotations from his movies, that have gone viral. Each explains the issue in simple, easy-to-understand terms.

“Gerrymandering has created an absurd reality,” Schwarzenegger says looking straight into the camera in one video, “where politicians now pick their voters instead of the voters picking their politicians.”

Through San Francisco’s CrowdPac, an online fundraising platform, he’s raising money online ($98,217 as of Friday) to help fund a legal challenge to Wisconsin gerrymandering that will be heard by the U.S. Supreme Court on Oct. 3. Justice Ruth Bader Ginsburg called the case “perhaps the most important” that the court will hear all year. Schwarzenegger will match what is raised online and likely kick in more support, as legal bills could approach $1 million.

He has spent much of the last week on the phone trying to arm-twist Republican members of Congress into signing onto an amicus brief in the Wisconsin case. It’s been a tough recruiting effort. While politicians tell him privately that they support him, they’re hesitant to publicly sign something that party leaders think could be their political death warrant.

Republica-12

ns have mastered the redistricting process thanks to a concerted effort in 2010 to win state-level races that enabled them to draw the political maps to their advantage. The result is a strong majority in the House of Representatives that Democrats are unlikely to break unless they can redraw the maps into more competitive districts after the next census in 2020, analysts said.

The GOP’s mastery of redistricting has helped them to dominate several levels of government. Since 2008, Democrats have lost more than 1,000 legislative seats across the country. Democrats hold 39 fewer seats in the House, three fewer in the Senate, and can claim 13 fewer Democratic governors than they did in 2007. The GOP controls 34 governor’s seats and dominates all branches of government in 26 states. Democrats control all three branches in only 15 states.

Schwarzenegger thinks that there will be more competitive races if the lines are drawn by non-politicians.

“Competition creates better performances,” Schwarzenegger said. “If someone is worried about competition, they will go out and perform better.”

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli