The president's unpopularity in California comes as no surprise; he lost the state to Hillary Clinton by more than 30 percentage points. But the poll made clear that he has done nothing to improve his standing since. In fact, it has worsened.
Antipathy toward the president was key to Democratic victories in Tuesday's general election in multiple states, but it is not clear from the poll whether the sentiment will influence contests here next year. Democrats are fighting for at least seven Republican-held congressional seats in California as part of their effort to take control of the House.
Gov. Jerry Brown, a Democrat, was rated as twice as popular as Trump; the state's Democratic senators, Dianne Feinstein and Kamala Harris, also were far more popular. Only Congress, perennially dismissed by Californians and now favorably looked upon by 1 in 10 voters, was less popular than the president.
Trump's positive impression of 20 percent meant that both his popularity and his job approval rating were substantially lower than the 31.6 percent of the vote he won in the state last November.
Among the voter groups most inclined to support Trump -- Republicans, white voters and those living in the Central Valley and the Inland Empire -- agreement with Trump's policies was consistently higher than his popularity or job approval rating. That reflected those voters' backing of Trump's policy objectives rather than his methods of accomplishing them.
Among Republicans, for example, 59 percent said they had a positive impression of the president, and 65 percent supported the job he has done in Washington. Yet 71 percent said they agreed with his policies.
"Even some people who like his policies probably don't like his tweeting ... don't like the sense of creating division and havoc," said Robert Shrum, director of the Jesse M. Unruh Institute of Politics at USC, which sponsored the poll.
On the other side of the political divide, however, views of Trump were unrelentingly harsh. Among members of the state's largest political party, the Democrats, only 4 percent had a positive view of Trump and only 5 percent approved of the job he is doing. Eight percent backed his policies.
Latinos, whom Trump has often criticized, were among the most critical of the president. Only 14 percent gave him positive ratings either personally or for his job, and only 15 percent backed his policies.
White voters, who make up most of the Republican Party, were more positive, although Trump remained in negative territory. Fewer than 3 in 10 voters approved of him or his handling of the job, and only 34 percent supported his policies. (The poll did not include enough voters from other racial groups to break them out independently.)