from the article linked to in the story in the tweet:
“Trump’s rhetoric — migrants “infest” and “invade our country” — is intended not only to intensify the anti-immigrant views of his supporters, but also to encourage liberals and Democrats to accuse him and his supporters of bigotry. Trump’s tactics are based on the conviction of many of his voters that opposition to immigration is not a form of racism. They deeply resent being called racist for anti-immigrant views they consider patriotic and, indeed, principled.”