Less than eight months before Election Day, the midterm landscape is still taking shape. It’s still not clear whether Democrats will have a good night (and potentially fall short of a majority) or a historic night in the House that puts them well over the top. But mounting evidence nationally and at the district level points to a Democratic advantage in a growing number of seats.

Democratic prospects improved in a handful of seats in Pennsylvania, thanks to a new, court-ordered map. And the party’s successes in state and local elections over the last 14 months demonstrate a surge in Democratic voters, particularly in blue areas, that could be problematic for Republican candidates in the fall. GOP incumbents in districts Hillary Clinton carried in 2016 might be particularly susceptible to increased Democratic enthusiasm.

Ratings for each House and Senate race are detailed in Roll Call’s Election Guide, while the specific ratings changes are listed below. As a reminder, the ratings aren’t set in stone and will necessarily adjust as the races and cycle progress.

We have shifted the Inside Elections ratings in 15 races toward the Democrats.

And in one race shifts toward the Republicans.