Whether Mr. Trump will survive into the new year is in doubt.
The poll numbers that have finally convinced voters that the once popular Mr. Trump is at his end have been coming for months, and were predicated, again, on a strong economy and Republicans in control of Congress.
But they were more than just an affirmation of his presidency: They were a sense of things getting better. Or so the public believed.
That interpretation has evaporated in the last couple weeks.
Even though an economy doing well, Republicans in control of Congress, and a struggling liberal agenda have made the economy the issue voters care about most, Trump and his supporters have shifted and pivoted and pivoted, making a variety of other issues — anything related to their preferred candidate — the dominant focus.
So their now-fading hope is that they will return to their original focus: His presidency.
Democrats think they may have the day that will convince more voters that the president is vulnerable: That Democratic tax legislation would grow the economy and both the president and Congress.
“It’s a really strong argument,” David Plouffe, a former top Obama adviser and Democrat, said in an interview.
If the Democrats win big in the House, while the Republicans gain the Senate, he said, Trump and his party will have lost the debate “completely.”
The Democrats’ tax overhaul, Mr. Plouffe said, would be a “series of maneuvers” that would show voters at home and on Wall Street that the president and Congress are making progress, as part of a slowly improving economy.