A quarter of California Republican voters polled said they would refuse to vote for Trump in November if he is the party’s nominee. Almost one-third of those backing Trump’s leading competitor, Texas Sen. Ted Cruz, said they would not cast a ballot for Trump. Voters who back Trump, meanwhile, are critical of Cruz, with only half holding a favorable impression of him.

That division sets up the potential of cascading losses down the ballot for Republicans already fighting the tide in one of the nation’s most Democratic states, including in a number of contested congressional districts.

Trump, passionately supported and deeply reviled in different corners of the electorate, has extended his reach among Republicans since the last USC/Los Angeles Times poll was taken in September. He now has the support of 37% of GOP voters surveyed, up from 24%.

Cruz, who was in single digits in the last poll behind candidates who have since left the race, is now at 30%. The third candidate, Ohio Gov. John Kasich, was invisible last September and is now at 12%.