STANFORD, Calif. (KTVU) - A poll of likely California voters shows Hillary Clinton with a 13-point lead over Bernie Sanders just one week before the primary, but researchers say there are some unknown factors that could tip the race either way.
The Stanford University Hoover Institution's Golden State Poll showed Clinton with 51% support compared to 38% for Sanders. The poll of 1,700 likely California voters was conducted between May 4th and May 16th with a margin of error +/- 3.47 percent.
Both Democratic candidates are investing heavily in the California June 7th primary. Sanders and Clinton are each planning a packed schedule of campaign stops through the state in the final week before the primary.
"We're still calling, we want to show a very big strong showing. We want to make sure California remains Clinton country," said Loreto Quevedo Dimaandal, co-founder of the Santa Clara County for Hillary volunteer group, which hosted a phone bank Tuesday evening in San Jose.
Hoover Institution researcher Bill Whalen says Clinton has history with Golden State voters.
"The Clintons have won in California each and every time they've been on a presidential ballot here and that includes her in 2008 when she ran against Barack Obama." Whalen said.
He says the poll shows that Hillary Clinton faces some big challenges, though, attracting independent and young voters.
"In our poll, Bernie Sanders swamps Hillary Clinton by a 2:1 margin with voters under the age of 30. But the question is can Bernie Sanders properly harness them on June the 7th?" Whalen said.
"While Sanders is trying to catch a large emotional wave, vis a vis these big rallies, has his campaign really done the nuts and bolts to organize to win a big state like California?" Whalen wonders, pointing out that the primary falls during a busy time for high school and college students who might be graduating, leaving, or still involved in their classwork.
"Some colleges like Stanford are still in session. Other colleges have ended for the year. Where are those kids going to be? Are they still going to be in California? Will they bother to vote on Tuesday?" Whalen asked.
In an interview with KTVU Clinton talked about why she plans to come back to California on Thursday, canceling campaign stops in New Jersey.
"I am proud to be campaigning across California and talking and listening mostly to what people are telling me about what they think the next President should do to be a really good partner for California," Clinton during a phone interview with KTVU anchor Gasia Mikaelian.
Clinton's campaign says she plans to be in California from June 2nd through June 5th and they are still finalizing details.
Sanders has a public rally scheduled June 1st in Palo Alto at Cubberley Community Center Fields at 11:30 a.m. That will be followed by another public event scheduled for Davis at 5 p.m.