He was referring to Feinstein's sudden opposition to the death penalty after decades of support for capital punishment, as well as support for recreational marijuana after opposing its legalization when it was on the ballot in 2016.
In the year leading up to this election, Feinstein seemed somewhat vulnerable for several reasons:
- Polls showed that her age (she'll be 85 in two weeks) concerned some voters and had some Democratic insiders wishing she'd retire.
- Her comment made in August expressing patience with President Trump. "I just hope he has the ability to learn and to change, and if he does he can be a good president. And that’s my hope," Feinstein said at a California Commonwealth Club event.
- Some saw Feinstein as out of sync with the state's increasingly deep-blue politics, in particular the energy coming from the left wing of the party, especially on health care.
But Feinstein leveraged her tremendous name ID, relatively positive approval ratings and Senate seniority to convince voters, donors and fellow Democrats to give her another term in office.
She also got a boost from two things outside her control: the "#MeToo" movement and the mass shooting at an open-air concert in Las Vegas that killed nearly 60 people.
As accusations of sexual harassment at the state Capitol mounted, it put de León, who was Senate president pro tempore until March, in the middle of that controversy. Making matters worse, one of the accused state senators shared an apartment with him in Sacramento. It took de León a while to get his political footing.
The Las Vegas mass shooting in October -- and ones after that at schools in Florida and Texas -- put Feinstein back in the national spotlight, reminding voters of her long support for stricter gun control.
Walking into those political headwinds was her main Democratic opponent, de León. Republican political consultant Sean Walsh said the November runoff could pose peril for both candidates and the party if de León is Feinstein's opponent.
"We could have a very acrimonious race between de León and Feinstein," Walsh said. "They both have something to lose when they run negative ads against each other."
Feinstein's decision to run for re-election may have also affected the governor's race.
"Antonio Villaraigosa might have run for the Senate rather than for governor, if she had retired," Walsh said. Now, he said, the two Democrats could be facing a bitter few months until November.
If de León faces off against Feinstein in November, there are doubts the outcome will be much different.
"Sen. de León's only hope is that we’re going to have a bigger and broader electorate in November," Kousser said, adding that it will not get any easier for de León to raise the money he needs for November.
"There's a huge risk in giving money to somebody who’s challenging an incumbent," Kousser said. "You’re either pouring good money after bad on a hopeless challenger or eroding any relationship you might have with a very powerful senator."
By moving away from her more conservative positions -- on issues like capital punishment, health care and recreational marijuana -- the former San Francisco mayor was trying to prevent de León from outflanking her on the left.
However, GOP operative Walsh said that could hurt Feinstein with voters who appreciate her moderation and centrist positions.
"When you try and do the Twister game and appeal to the flavor of the day, you really hurt yourself," Walsh said.