SACRAMENTO, Calif. (AP) — California U.S. Sen. Dianne Feinstein says she no longer backs the death penalty, a reversal of decades-long support that comes during a primary campaign where her stiffest challenge is from a fellow Democrat who is trying to outflank her with the party's base. 

"It became crystal clear to me that the risk of unequal application is high and its effect on deterrence is low," she said in a Wednesday statement, adding that the change came "several years ago."

But she hasn't publicly discussed it until now, just weeks before the June 5 primary in her bid for a fifth full term in Washington. Feinstein's toughest challenger is Democratic state Sen. Kevin de Leon, who argues she is out of touch with California values.

The two candidates with the highest number of votes in the primary advance to November regardless of party, and there are no prominent Republicans in the contest.

De Leon blocked Feinstein from receiving the California Democratic Party's endorsement at its annual convention in February, a window into her troubles with some of the activist base. De Leon seized on her death penalty shift as further evidence that Feinstein is worried about her base of support.

"This latest flip on the death penalty is yet another appeal to California voters who have outgrown her centrist bent," de Leon spokesman Jonathan Underland said.

Still, Feinstein remains popular and has a significant edge on de Leon in name recognition and money, two critical elements for a successful statewide campaign. She's run successful campaigns in the past by picking up Democrats as well as California's independent voters, who now make up almost as large a share of the electorate as Republicans.

Her prior support for the death penalty is a prime example of her willingness to shun the party's base in favor of capturing wider support.

Running for governor in 1990, she aggressively touted her support for capital punishment at the ire of Democratic activists, who booed her at the party's annual convention.

She ran a television ad declaring that she was "the only Democrat for governor for the death penalty."

She won the party's nomination but lost the general election. She maintained the position in her successful 1992 campaign for U.S. Senate and in subsequent campaigns.

California has since become a more heavily Democratic state.

Feinstein gave a nod to the state's changes earlier this year when appearing to shift her stance slightly on marijuana. She vehemently opposed a state proposition to legalize recreational marijuana in 2016, but said in early May that she would consider legislation granting protection to states that have legalized the drug.

Her office did not offer a clear answer on whether she broadly supports legalized recreational marijuana.

De Leon similarly pointed to that change as evidence that Feinstein is out of touch with today's voters.