As an old foggie, I have seen when those up for reelection in congress try to separate or distant themselves from the president in order to give one a better chance at reelection, it doesn't work.

"Republicans are really fed up': GOP increasingly splits with Trump as his polls drag"

https://news.yahoo.com/republicans-really-fed-gop-increasingly-100032722.html

One usually loses some support from those voters who are loyal to the president, it also doesn't help gain votes from independents. The opposite party folks aren't going to vote for you anyway.

Bottom line, if you're going to get buried by supporting your president, you're still going to get buried by trying to distant yourself from your president. What this all tells me, the Republicans know they're in deep doo doo when it comes to November.
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It's high past time that we start electing Americans to congress and the presidency who put America first instead of their political party. For way too long we have been electing Republicans and Democrats who happen to be Americans instead of Americans who happen to be Republicans and Democrats.