Bottom Line: Pay more attention to Trump job approval rating among independent voters than the overall margin in the congressional ballot. Unless or until Trump improves his standing among independents, Republicans in Congress shouldn’t expect to see an improvement in their ballot standing with them.

It’s also important to remember that the generic ballot question is just that: generic. There are some districts and states where Trump’s job approval rating among independent voters is going to be better and some where it is going to be worse. Intensity of support/opposition to Trump among independents matters as well. The latest Marist poll finds 40 percent of independent voters ‘strongly’ disapprove of the job Trump is doing, compared with just 20 percent who ‘strongly’ approve. This means that the overall independent pool of voters could be more anti-Trump than the top line numbers suggest.

We also know that assumptions about turn-out matter too. For example, if Republicans have a bigger vote share in a state or district, they may be able to withstand a poor showing among independents.