The greatest threat to Republicans in the midterms: Positive poll numbers

Midterm elections invariably favor the party that’s not in the White House. There is always more passion from opposition to the executive branch that translates into victories in the legislative branch. This has helped maintain the ebb and flow of power between the two parties that is incongruent between the legislative and executive branches.
In other words, people who were pumped about voting for President Trump are less pumped now than the people who want to put a check on his power.
This election year seemed to be heading in the same direction as previous midterm election years. Then, a strange thing happened. Democrats went full-blown unhinged during the Brett Kavanaugh confirmation process. Moreover, Republican voters were reminded that the President is powerless to put conservatives on the Supreme Court if the Democrats take control of the Senate.
Polls since Kavanaugh’s confirmation make prospects look great for Republicans to hold the Senate Majority and decent for them to hold a House majority. Just a month ago, the potential for a blue wave put both at risk.
Now, the thing that can hurt the Republicans the most is expression of positive sentiment (or at least less negative sentiment than the Democrats) in the form of favorable poll numbers. If Republican voters think they’re going to win these elections, they’re less likely to actually get out and vote.
Democrats don’t have this problem. Their hatred for President Trump and their desire to regain control of the House and Senate is not going to fade. If anything, these poll numbers are going to put a fire under them that will prompt them to force others around them to vote as well.
Republicans may have the momentum, but three weeks is a long time to try to sustain it now that the Kavanaugh debacle is mostly over. Republicans won that round, so it’s very easy for complacency to set in.
If the GOP really wants to hold majorities, they must generate a lot more enthusiasm around election day. If polls won elections, Hillary Clinton would be President, the Senate would be blue, and Merrick Garland would be on the Supreme Court.