This chart is from the new NBC News / Wall Street Journal Poll -- done between June 17th and 20th of a random national sample of 900 adults (including 765 registered voters) with a 3.27 point margin of error.
It shows that Trump still has a negative net job approval rating of 15 points with the general public (40% approving and 55% disapproving). He has the approval of those in his own party (82%), but only 35% among Independents and 6% among Democrats.
This won't matter to Republicans in overwhelmingly safe districts in 2018. But it should worry the Republicans in the districts where they won by only a single digit (the purple districts). It means they won't be helped by clinging to the coattails of Trump. In fact, being closely allied with Trump would hurt them with Independents and Democrats (who together make up the majority in purple districts).