The chart above shows the results of the new NPR / PBS NewsHour / Marist Poll -- done between January 10th and 13th of a national sample of 1,023 respondents, with a 3.8 point margin of error.
If the 2020 election was being held right now, Donald Trump would suffer a crushing defeat. Only 30% of registered voters say they would definitely vote for Trump, while 57% of them say they would definitely vote against him.
Those are some terrible numbers, but Trump has nearly two years to improve them. The problem is that he doesn't seem interested in appealing to a broader group of voters. His actions seem designed to appeal only to his small base (which is not large enough to get him re-elected).