Among Democrats , education has emerged as a key dividing line on economic policy. Ms. Warren’s tax is overwhelmingly popular ( 86 percent support ) with Democratic voters who have graduate degrees. Among voters with a high school diploma or less, the policy is still popular, but meaningfully less so, drawing 75 percent support.

Accordingly, less-educated voters are also less likely to say they favor Ms. Warren on the economy. That fits with other polling that has found the Massachusetts senator struggling to win over voters without a college degree.

Strikingly for a candidate who has put so much emphasis on the economy, Ms. Warren is viewed with caution by voters who care the most about the economy, and by those who are most worried about it. Among Democrats who say they are “very concerned” about losing their job, for example, 15 percent say they would trust Ms. Warren most on the economy out of all the Democratic candidates, compared with 23 percent of other Democratic voters.

Those struggles for Ms. Warren may partly reflect another important divide in the Democratic electorate: race. Black and Hispanic voters tend to rate the economy more highly as an issue than their white counterparts. They are also less likely to trust Ms. Warren on the economy.

Black and Hispanic voters are more likely to choose former Vice President Joseph R. Biden Jr. as the candidate they would trust on the economy. So are voters who say they are concerned about their jobs or their economic prospects. But voters’ preferences don’t fall neatly along ideological lines: Those same groups also tend to give high ratings to Mr. Sanders, who is closer to Ms. Warren than to Mr. Biden on most policy matters.