In some cases, the Trump administration has said existing federal law already gives the president all the power he needs to act.

Coleman Hughes in Queens, N.Y., on Tuesday. Mr. Hughes has emerged as something of a rarity in the tense national conversation over how race should factor into public policy.

Sally Kornbluth, the president of Massachusetts Institute of Technology, testified before Congress last month.

Nielsen’s preliminary figures for the Republican presidential debate on Wednesday were a few million below the total for the first debate last month.