President Trump’s $1.5 trillion tax cut was supposed to be a big selling point for congressional Republicans in the midterm elections. Instead, it appears to have done more to hurt than help Republicans in high-tax districts across California, New Jersey, Virginia and other states.

House Republicans suffered heavy Election Day losses in districts where large concentrations of taxpayers claim a popular tax break — the state and local tax deduction — which the law capped at $10,000 per household. The new limit resulted in an effective tax increase for high-earning residents of high-tax states who claim more than $10,000 per year in SALT.

Democrats swept four Republican-held districts in Orange County, Calif., where at least 40 percent of taxpayers claim the SALT tax break, defeating a pair of Republican incumbents and winning seats vacated by Representatives Ed Royce and Darrell Issa. Those districts include longtime Republican strongholds, like Newport Beach, and rank among the country’s largest users of the state and local tax break.

Representative Barbara Comstock lost a seat in Northern Virginia, where more than half of taxpayers claim the SALT deduction, by nearly 13 points. Representative Erik Paulsen of Minnesota, a huge champion of the tax bill, lost by about the same margin in a district where 40 percent of taxpayers claim the deduction.