Transcript for Will GOP tax plan help or hurt GOP in 2018?
This week, the president's biggest legislative win yet. But behind all the back slaping and self-congratulations, it's an anxious time for Republicans and to the white house. Several year-end polls show the president's approval rating at or near his all-time low. And historically low for a first-year president. This, as the political landscape is set to change. With over two dozen Republicans already saying they won't seek re-election to congress next year. But Republicans are holding on to the tax bill as their ticket to success. And at least for this week, they had a lot to celebrate. A bang of the speaker's gavel. A stroke of the president's pen. That, a big tax cut, a big political victory. It's going to be a tremendous thing for the American people. It's going to be fantastic for the economy. Reporter: The president says the middle class will benefit the most. The biggest tax breaks go to corporations and the wealthy. Polls show the vast majority of Americans don't like the plan. Republicans are betting that more jobs and more take-home pay will turn an unpopular bill into a political winner. We can't sell this to the American people, we ought to go into another line of work. Reporter: Not a single Democrat voted for the trump tax cuts in the house or the senate. They think they've found a defining issue for the 2018 midterm elections. Don't throw me a crumb and tell me that I'm benefiting when you're robbing the future by increasing the debt, rewarding the rich, as you ransack the middle class. Reporter: The other big battleground? Over Obamacare. The president claims he killed it this week by getting rid of the requirement that all Americans buy health insurance or pay a penalty. I hate to say this, but, we essentially repealed Obamacare. Reporter: In reality, almost all of Obamacare remains in place. And 4ehealthcare.gov shows almost as many signups as last year. It's fun when you win. Reporter: After a year of political infighting. For now, at least, all is forgiven.
This transcript has been automatically generated and may not be 100% accurate.