Los Angeles (CNN) In yet another sign of trouble for Sen. Kamala Harris in the 2020 presidential race, the California Democrat has slid from an enviable front-runner position in her home state into the single digits in a new poll of likely voters in the Golden State.

As the state's March 5 primary draws closer, Sen. Elizabeth Warren of Massachusetts (23%), former Vice President Joe Biden (22%) and Sen. Bernie Sanders of Vermont (21%) are now tied as the leaders in the field among likely voters who are either registered as Democrats or identify as Democratic-leaning independents in the new Public Policy Institute of California poll, which was conducted in mid- to late September after Harris' uneven performance in the last debate.

Harris tumbled from 19% in July to 8% in the new poll by the institute, failing to sustain the momentum she sparked with her first debate performance in June. She lost significant ground over the summer, while her chief rivals all solidified their standing among California voters.

In the July poll, Warren was at 15%, Sanders was at 12% and Biden was at 11% -- all trailing Harris, who got both a fundraising and a polling bounce after she delivered a fiery performance in the first debate in Miami by questioning the former vice president's past opposition to busing for the purpose of desegregating schools.

While it is often said that California tends to reflect the national state of play of the presidential race -- because it is so expensive to wage an intensive campaign in this vast and diverse state -- the new Public Policy Institute of California poll underscores that Harris does not seem to be drawing any advantage from the fact that she served as the state's attorney general and continues to serve constituents as the state's junior US senator.

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