With three days of attacks on four liberal, minority freshman congresswomen, President Trump and the Republicans have sent the clearest signal yet that their approach to 2020 will be a racially divisive reprise of the strategy that helped Mr. Trump narrowly capture the White House in 2016.

It is the kind of fight that the president relishes. He has told aides, in fact, that he is pleased with the Democratic reaction to his attacks, boasting that he is “marrying” the House Speaker Nancy Pelosi and the Democratic Party to the four congresswomen known as “the Squad.”…

Aides to Mr. Trump’s campaign conceded that the president’s tweets about the four women on Sunday were not helpful, were difficult to defend and caught them off guard. They would have preferred he had not tweeted that the four women, all racial and ethnic minorities, should “go back” to their own countries. Only one, Ms. Omar, was born in a foreign country.