As President Trump again ratchets up trade tensions with China and Canada, he has the strong backing of Republican voters. But he risks putting his party’s congressional candidates — many of whom are more supportive of free trade — in a bind.

Top Republicans in Congress love Mr. Trump’s tax cuts, but they do not love the tariffs that have become the centerpiece of his trade policy. This combination is a classic conservative position that favors low taxes, whether on income or on imports.

Few Americans outside Washington share that view.

Republican voters across the country approve of Mr. Trump’s tariffs almost as much as they approve of his tax cuts, according to a survey conducted for The New York Times in early September by the online polling firm SurveyMonkey. Democrats disapprove of tariffs and tax cuts by an equally enthusiastic degree. Independents are more split, but they lean toward the Democratic position on both issues.