(CBS SF) – A new poll shows Sen. Bernie Sanders expanding his lead over his rivals in California, a little more than a month before the state’s Democratic presidential primary.

According to the UC Berkeley Institute of Governmental Studies, Sanders is leading with 26 percent support ahead of the state’s Super Tuesday primary on March 3.

Sen. Elizabeth Warren of Massachusetts is second in the poll, at 20 percent. Rounding out the top 3 is former Vice President Joe Biden, at 15 percent. The previous Berkeley poll taken in late November showed Sanders with 24 percent support, two points ahead of Warren and 10 points ahead of Biden.

Five candidates, former South Bend, Indiana Mayor Pete Buttigieg, former New York City Mayor Michael Bloomberg, Sen. Amy Klobuchar of Minnesota, and businessmen Andrew Yang and Tom Steyer were polling in the single digits. Twelve percent of those surveyed were undecided.

KPIX 5 spoke with Mark DiCamillo, the director of the poll, about the lead Sanders has over Warren with less than five weeks to go.

“It’s a lead, it’s a significant lead. This is a very large poll, we had about 2,800 people in the survey. So there’s no question if the election were today, in my mind that Bernie would win,” DiCamillo said. “But we’ll have to see how Iowa and New Hampshire shake out.”

Sanders’ campaign announced it would launch a $2.5 million TV ad campaign in both California and Texas, marking the campaign’s first ad buy in Super Tuesday states.

According to the California Secretary of State’s Office, the last day to register to vote in the March primary is February 18th. Democrats, along with voters who are registered with “No Party Preference” are eligible to vote in the Democratic primary.