A big-money ad war in California’s governor’s race officially started Thursday when a billionaire-backed independent expenditure campaign touting Democrat Antonio Villaraigosa launched a “seven-figure” buy that will blast a commercial on TV screens statewide for at least a week.

The 30-second spot, titled “Ahead,” is intended to introduce the former Los Angeles mayor to voters who may not have been paying close attention to the June 5 primary race. It says violent crime in L.A. dropped by nearly 50 percent during Villaraigosa’s time in office, from 2005 to 2013, an assertion that the nonpartisan fact-checkers at Politifact California rate as “mostly true.”

The ad is funded by an organization called Families and Teachers for Antonio Villaraigosa for Governor 2018, which is run by the California Charter Schools Association Advocates. Last week, Netflix CEO Reed Hastings pledged $7 million to the independent group, and Los Angeles real estate entrepreneur Eli Broad promised $1.5 million.

The money is helpful to the Villaraigosa camp, which had only $5.9 million cash on hand at the end of 2017— less than a third of what Lt. Gov. Gavin Newsom had. Campaigns and independent expenditure group are banned from coordinating their activities or co-mingling funds.

Most polls show that Newsom is leading the race, with Villaraigosa battling with John Cox, a GOP businessman from Rancho Santa Fe (San Diego County), for the other spot in the general election.

But backers of the pro-Villaraigosa independent expenditure group think voters are still searching for their favorite candidate in a race that has yet to catch fire. Newsom isn’t running away from the field, and about a third of voters remain undecided, said Josh Pulliam, a political consultant running the independent group.

“Polling over the past two years shows Gavin hasn’t gained support, and most recently shows Gavin losing votes,” Pulliam said. “People are looking for a different kind of governor. We want to introduce them to Antonio.”

In politics, the soft-focus biographical ads usually come first. Then, they’re followed by hard-hitting attacks on opponents. It won’t be long before we find out if that pattern holds true here.

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