In February, congressional approval was at a several-year high at 28% approval. That has now dropped back down to 20% approval. The drop is due mainly to Republican disappointment in the 115th Congress. Back in February, the Republicans thought they could finally pass some of their programs since they controlled both houses of Congress (and had a GOP president).
But with the failure of the "repeal and replace" plan for health care, and the inability of Congress to agree on anything else, the GOP base is once again losing their patience with Congress. Their approval has dropped from 50% in February to only 31% in April. Both Independents (20%) and Democrats (10%) continue to have an even worse view of this Congress.
The chart above is from the Gallup Poll -- done between April 6th and 9th of a random national sample of 1,019 adults, with a 4 point margin of error.