Over the next two months, Democratic and Republican donors are expected to funnel as much as $200 million into a California ballot fight that could heavily shape which party wins control of the U.S. House next year.

It is an enormous amount of cash to raise in such a brief amount of time, but one that befits the stakes of the race.

That was the message that Gavin Newsom, the state’s governor and the face of the ballot measure to gerrymander districts in California, delivered when he made a surprise appearance in an Aug. 18 briefing for advisers to the state’s billionaire donors.

Mr. Newsom had not been listed on the “campaign briefing” advertised to the donors, but after Jim DeBoo, his top campaign adviser, ran through the polling, Mr. Newsom hopped in the Zoom meeting to encourage the richest Californians to get into the fight.

Democrats, he told more than 20 donor advisers that Monday afternoon, could not unilaterally disarm as Republicans drew new maps to gerrymander Texas to their advantage, according to four people on the call. So he had to raise millions. Fast.

The surprise November election has jostled a sleepy political fund-raising class, particularly among Democrats, who are still recovering from the doldrums after a heartbreaking 2024 campaign.