The former secretary of state begins a five-day swing through California on Thursday that she hopes will result in a victory that convinces Sanders and his supporters that it's time to unite against Donald Trump.
But Sanders shows no signs of going away. The Vermont senator, who has used a bus to traverse the state, headlined over 27 rallies and forums last month, and is expected to have a jam packed schedule the week before Tuesday's primary.
Clinton had planned to campaign this week in New Jersey ahead of that state's Tuesday primary, but the campaign decided instead to fly to San Diego for a speech on foreign policy that will also go directly after Trump, as well as tout her own experience as secretary of state.
Clinton will argue that the choice in 2016 "goes beyond partisanship" because Trump is "unlike any presidential nominee we've seen in modern times and he is fundamentally unfit for the job," Jake Sullivan, Clinton's senior policy adviser, said in a statement.
The speech shows the predicament Clinton is currently in: She is committing five days to battle Sanders in California, a solidly Democratic general election state, while also trying to focus on the presumptive GOP nominee.
"I wonder why Secretary Clinton and her husband Bill are back in California," Sanders sarcastically told reporters Wednesday in Spreckels, California. "I thought we had lost it. It was all over but I guess Secretary Clinton maybe is looking at some polling would suggest otherwise."
The non-stop campaigning -- coupled with a small ad buy, dozens of surrogate events and targeted get out the vote efforts -- is more than Clinton's senior aides expected to commit to California months ago.
Aides acknowledge Clinton could lose the state, despite polls showing her up narrowly. Internal polling has Clinton up double digits in New Jersey, aides said, and their thinking is that it "doesn't make sense" to be in the Garden State while the race in California is still "tight."
An NBC/Wall Street Journal/Marist Poll released Wednesday found the race neck-and-neck
, with Clinton holding a 2 point lead over Sanders, 49% to 47%.
"Clearly California is a big state and I am going to do everything I can to meet as many voters as possible," Clinton told CNN on Tuesday. "I was proud today to be endorsed by Gov. Jerry Brown and we are going to keep working as diligently and tirelessly as we can to get as much voters to turn out and vote for me next Tuesday."
Brown, the Democratic governor, endorsed Clinton this week
, arguing she has the best chance to beat Trump in the fall. Sanders replied that Brown, who challenged Bill Clinton for the 1992 Democratic presidential nomination, is part of the establishment backing the front-runner.
"I will tell you that in every state that we have gone into, we have taken on the entire Democratic establishment," Sanders said in response to a question about Brown's endorsement. "It's not surprising to me that, you know, we will have the Democratic establishment supporting Hillary Clinton."
Sanders fights superdelegate system
At the same time, the former secretary of state doesn't need to win California — or even come that close — to win the nomination on Tuesday.
Clinton currently needs 70 delegates to clinch the Democratic nomination, according to CNN's estimate, a number she is likely to win from the New Jersey primary. Because results from New Jersey will come in hours before California, top aides assume that most news networks will call the Democratic Primary on Tuesday before results come in from the West Coast. And since delegates are awarded proportionally — this isn't winner-take-all as some of the big GOP contests were -- a Sanders win in California wouldn't make a much of a dent in her lead.
But Clinton aides said they were aware that losing California to Sanders would be embarrassing for her campaign and could hand the Vermont senator the needed momentum to justify staying in the race through Democratic convention in July.
Sanders has continued to rail on the superdelegate system throughout California, blasting the "Democratic establishment" for allowing Democratic elected officials and party insiders to have a vote in who the party nominates.
"It is a pretty dumb system," Sanders said in Monterey, California on Tuesday about the fact so many party insiders are behind Clinton. "It's an unfair system, it's a dumb system, and it's a system we will change."
But Sanders, with a win in California, hopes he will be able to turn the system to his advantage. Sanders and his aides have argued for weeks that a win in California will help the Vermont senator convince super delegates currently backing Clinton to support him instead.
So far, though, the effort has been largely fruitless: Clinton has maintained a sizeable superdelegate lead and Sanders has only been able to flip one delegate.
In an attempt to lower the stakes in California, the Clinton campaign has instructed surrogates to say that they "expect" California to be a close contest, but to downplay its importance in picking the eventual nominee.
"Even if Senator Sanders wins each of the remaining contests by 32 points, Hillary Clinton will still have earned the majority of pledged delegates and popular vote," read talking points distributed to supporters on Tuesday.
Clinton will continue to largely ignore Sanders in California, aides said, a tactic Clinton employed in late May during a string of events in Los Angeles and the Bay Area.
Clinton, instead, will focus almost exclusively on Trump, casting him as a "fraud," as she did in New Jersey on Wednesday. After workshopping different ways to take on Trump
, Clinton and her aides have landed on trying to discredit him early as a businessman who only protects his own interests, a man who is incapable of working with others and a candidate who would pose a risk to national security.
Her speech Thursday will begin drawing from her record as secretary of state, defending what some Republicans have said will be a liability for her in a race against Trump.
"She will reflect on her experience making the tough calls and doing the hard work of protecting our country," Sullivan said. "She'll reaffirm her conviction that strong, principled American leadership makes both the United States and the world more secure."
Sullivan added: "And you will hear in her speech a confidence in America and our capacity to overcome the challenges we face while staying true to our values -- a strong contrast to Donald Trump's incessant trash-talking of America."
Sanders, however, is expected to continue to draw contrast with Clinton as primary day in California gets closer. He spent Wednesday hitting Clinton for opposing an outright ban on hydraulic fracturing, a controversial drilling tactic.
"Sec. Clinton does not support a ban on fracking," Sanders tweeted on Wednesday. "Instead, she would simply impose a few more regulations on it. Not good enough."