special elections, all in very red districts this far out isn't an indication of how the midterms will go. Actually this far out, there are no concrete indications whatsoever. Who knows, the economy may be booming come November of next year and there may be plenty of jobs available. I could tell you what probably would happen today with Trump's approval rating as low as it is, no Hillary Clinton to negate the negative image of Trump, the drop in party affiliation for the GOP and so on. But all that is dynamic with the exception of no Hillary Clinton to negate the dislike for Trump. All change constantly.
Here's an example:
Democratic Edge in Party Affiliation Up to Seven Points | Gallup
A seven point lead in party affiliation is a big thing. Back in November of last year the Democrats had the lead in party affiliation, but only three points, 46-43 and that pretty much equated to Hillary's two point win in the popular vote. I don't like the idea of Gallup including leaners. I like to use straight party affiliation, then the independent lean Republican and lean Democrat with the last being pure or true independents with no leans.
Also here is a list of presidential approval rating and what happened in the midterms in congress.
1970 Nixon 58% Minus 2 senate Plus 12 House seats
1974 Ford 42% Minus 5 senate Minus 48 House seats
1978 Carter 49% Minus 3 senate Minus 5 House seats
1982 Reagan 43% Plus 1 senate Minus 26 House seats
1986 Reagan 47% Minus 8 senate Minus 5 House seats
1990 Bush I 54% Minus 1 senate Minus 8 House seats
1994 Clinton 41% Minus 9 senate Minus 54 House seats
1998 Clinton 66% Senate no change Plus 4 House seats
2002 Bush II 63% Plus 1 senate Plus 8 House seats
2006 Bush II 37% Minus 6 senate Minus 33 House seats
2010 Obama 44% Minus 6 senate Minus 63 House seats
2014 Obama 41% Minus 9 senate Minus 13 House seats
People say Trump is unique and history doesn't apply. I say, yes, last years presidential election was unique and conventional wisdom went out the window due to the fact both candidates were disliked by around 60% of the electorate. But 2018 won't have Hillary Clinton around to negate that dislike of Trump. The absence of Hillary Clinton puts next year's midterms back into the historical and conventional wisdom category.