There is a lot of angst already over the midterms, and even beginning over the 2020 race. There is something that everybody has overlooked, and that is; laws, rules and regulations are no longer decided by city councils, legislatures or the US Congress. What do I mean by that? Simply this, everything is now decided by a court, so Judges are the final arbiters of what becomes law.
Look at how many times the GOP sued Obama, then look at how many times Trump has been sued already by Democrats, Democratic AG's and liberal advocacy groups. No matter what laws are passed by wh**ever level of Government, someone is going to sue over them, and a Judge will end up deciding if they will become law, or not. Republicans were smart to split their efforts between campaigning against everything Democrats have done, and campaigning for Judgeships. By packing the courts with partisans and ideologues, the GOP's agenda will outlast their control over legislatures and the Congress.
That's right, even if the GOP should lose control of both chambers of Congress, and many State legislatures, their agenda will persist. How? By suing over every effort by the new rulers to undo what they've done/started, knowing that their folks are sitting the benches that will ultimately decide what happens. That explains the near apoplectic fervor over getting another Conservative on the US Supreme Court..................who are the final arbiters over all of the lower courts.
There is a slight risk to this strategy though. Should the GOP agenda and conservative ideology not deliver the promised rewards for all Americans, and the majority of them get upset enough, there might be enough pressure applied to see some forced resignations, retirements and/or impeachments of Federal Judges, including SCOTUS. The GOP took advantage of the Democratic parties complacency, apathy and arrogance ( brilliantly illustrated by H. Clinton describing Trump supporters as "deplorable"), quietly filling every conceivable court bench with ideologues ( all of whom promised to follow the law, not partisan doctrine
).
So, Republicans, especially Conservatives, need not worry too much about the midterms, because even if the worst should happen...............it will take Democrats/liberals/progressives ( or whoever succeeds the current rulers) decades to undo their agenda.