San Francisco congressional candidate Saikat Chakrabarti has donated $500,000 to a labor-backed ballot measure to overhaul the city’s tax system, days after Google co-founder Sergey Brin donated the same amount to a rival proposition.

Chakrabarti told the Chronicle he gave his personal money after “waking up” to headlines about Brin’s donation. 

“I thought, if I can, I’m going to fight back, and I’m going to match them,” Chakrabarti said in an interview. 

On Tuesday, Brin, who mostly lives in Nevada but has investments in San Francisco, chipped in half a million dollars to a campaign supporting Prop C, which would exempt more city businesses from taxes.

Chakrabarti, a think tank executive, said he matched Brin’s donation, contributing to a campaign supporting Prop D, a competing measure that would increase taxes on businesses.

Its supporters have dubbed Prop D the “Overpaid CEO” tax. Prop C, which is supported by business groups, was initiated as a countermeasure. If both measures pass, only the one with more votes would take effect.

Prop D and Prop C are on the June 2 primary ballot, where Chakrabarti is also running against state Senator Scott Wiener and San Francisco Supervisor Connie Chan to replace Speaker Emerita Nancy Pelosi in Congress.

Brin and Chakrabarti’s donations underscore the stakes around the tax fight, which has escalated with less than two weeks to go before election day.

Brin joined a host of other tech elites who have donated to moderate political causes like Prop C, but Chakrabarti said he contributed because he doesn’t want tech money to continue influencing elections.

“I keep seeing these tech oligarchs spending money to buy out votes in Congress, to buy elections and it’s to hoard more wealth and rig the system in their favor,” Chakrabarti said Friday. “It’s fundamentally about controlling politics. We have to fight that at every level.”