The Republican-controlled 115th Congress remains very unpopular with the public. Only a tiny 11% approve of the job Congress is doing, while 63% say they disapprove. And those numbers are after the Congress passed the tax reform bill. It seems that the tax bill didn't improve the public's opinion of Congress.
Americans aren't thrilled with the performance of either party in Congress, but they have a lower opinion of the job Republicans have done than the job Democrats have done. With such a low opinion of Congress, and the fact that Democrats aren't viewed as unfavorably as Republicans, I think the opportunity for Democrats to flip Congress in this year's elections remains a real possibility.
The numbers in the chart above are from the latest Economist / YouGov Poll -- done between January 28th and 30th of a random national sample of 1,500 adults, with a 3 point margin of error.