Ms. Harris leads by four points in Pennsylvania, just as she did immediately after the final debate. Mr. Trump leads by six points in Arizona, about the same as the five-point lead he held three weeks ago.

Trump has 51 percent of support among likely voters in Arizona to Harris’s 46 percent, while 2,000 miles away in Pennsylvania, the vice president appears to be consolidating a lead of 50 percent to Trump’s 47 percent, having led in that state for the third consecutive poll.