A campaign mail piece sent to Sacramento voters this week attacks mayoral Darrell Steinberg, describing him as anti-farmworker.

The ad was produced by the California Taxpayers Coalition, a political committee operated by a San Diego-area consultant. Money for the independent expenditure came from the Sacramento Metropolitan Chamber of Commerce’s political action committee; the Western Electrical Contractors Association, a coalition of anti-union contractors; and Central Valley farming giant Gerawan Farming, which has battled Steinberg and the United Farm Workers union in the past.

The three groups combined to contribute $65,000 for the ad and two others received in the last week, according to campaign finance records filed with the California secretary of state.

Steinberg’s chief opponent in Tuesday’s primary, Sacramento City Councilwoman Angelique Ashby, was not responsible for the mailer. The Metro Chamber has endorsed her candidacy.

Below is the text of the ad and an analysis.

Text: The mailer shows an image of Steinberg in a business suit placed over farmworkers in a field. At the top of the page, the mailer reads: “Steinberg wrote a bill to strip farmworkers of their voting rights.”

“Darrell Steinberg, on behalf of powerful special interests, wrote a bill that would have stripped farmworkers of their right to vote on their own contracts – a right given to every other union member in California,” it continues.

Another passage reads: “Steinberg worked to strip Latino farmworkers of their voting rights – he put special interests before people. That’s the Steinberg Way.”

The last sentence, at the bottom of the page, reads: “Darrell Steinberg’s Time as Senate Leader: more corruption, less ethics, and fewer voting rights for Latino farmworkers.”

Analysis: The ad cites Senate Bill 25 as its evidence of Steinberg stripping voting rights of farmworkers. The bill was authored by Steinberg and vetoed by Gov. Jerry Brown in 2014. The bill was supported by unions, including the United Farm Workers, who have blasted the ad’s message.

SB 25 would have allowed the state’s Agriculture Labor Relations Board to implement farm labor contracts secured through mandatory mediation even if employers appealed. Farmers who opposed the bill argued it would have limited workers’ ability to vote on contracts before they were imposed, but the bill was not crafted to impact voting rights.