Poizner, California's insurance commissioner, said Whitman's negative ads targeting him will result in a backlash.
"She's clearly trying to buy the election," Poizner said.
Poizner, who is lagging behind Whitman in polls, said he has "plenty of money" and plans to spend it before the June primary.
"We've concentrated our funds here at the end," he said. "We're going to be very aggressive now."
Poizner earlier in the day told a a law-enforcement group meeting at the Sheraton Grand in Sacramento that he wants to improve the state's economy with across-the-board tax cuts. Even as the state faces a big deficit, he said such a move would create jobs.
Democrat Jerry Brown, the state's attorney general and a former governor, is also running.
This article originally appeared on KCRA.com.