Republicans are taking their own selves down. They have been for the past ten or more years. Look at what the Republicans did in North Carolina and Wisconsin.
North Carolina Fraud Scandal Casts Shadow Over the Primary, Too
"ELIZABETHTOWN, N.C. — Democrats have been quick to argue that their losing candidate for Congress in North Carolina’s Ninth District may have been a victim of election fraud. But there might be a Republican victim as well".
http://www.nytimes.com/2018/12/12/us/politics/north-carolina-republican-primary-fraud.html
Wisconsin Gov. Walker signs lame-duck legislation to weaken incoming Democratic governor.
"Wisconsin Gov. Scott Walker (R) on Friday signed sweeping legislation that weakens the power of the incoming Democratic governor and attorney general, dismissing a national outcry over what Democrats have characterized as a blatant power grab".
Then you have Trump lying nearly every breath he takes.
Mick Mulvaney Can’t Save Donald Trump From His Own Actions and Lies
"Donald Trump is an incorrigible liar, of course, but this was the week when some of his whoppers finally caught up with him, leaving him in serious legal and political peril".
http://www.newyorker.com/news/our-columnists/mick-mulvaney-cant-save-donald-trump-from-his-own-actions-and-lies
Republicans are taking themselves down. Nobody is doing it for them. Republicans and their crooked actions brought this on. They opened the door for it.