I think we have all learned a little something about the accuracy of these polls over the last few years. The numbers seem to depend on who is doing the poll and how they have structured it (mainly who they are polling). Many polls take a very small sampling of the population. One I read about recently polled about 1,400 people some of which were not registered to vote.
Much of what I read predicts some doom and gloom for Democrats come next November. One I read today, sees the house losing their Democratic majority while the Senate will gain Democratic voters. If that happens, we are certain to have another two years of Congress basically doing nothing - passing/approving no bills. The Senate does have the responsibility of approving some things on their own, such as appointments.