The rank and file republicans are not that bright. But they're not behind any of this. For example, consider that the koch machine---meaning the family and all it's tentacles---there are very bright people working to accomplish their goals, which are not related to constitutional guarantees of individual rights. The billionaires of this country, with few exceptions, involved in the efforts to overturn a constitutional republic in favor of the fascist oligarchy that serves themselves and not the people, were exposed in various ways including the paradise papers as being involved with Russia and in having big investments depending on Russian success. The republican congress are known to be taking instruction from these groups. The kochs et al have huge financial stakes in seeing sanctions against Russia ended. The republican congress voted FOR ending sanctions, but does anyone really believe they didn't know before the vote that their pseudodent wouldn't sign? The congressional approval and subsequent white house denial is a savvy political move----the US oligarchy is who is fighting the Constitution and striving to shut down an investigation that could result in strenuous US government acts against Russia and therefore against their investments in and with Russia. The sanctions are the key---Putin's personal fortune as well as those fortunes of the kochs and their various buddies are threatened by the sanctions AND by the investigation.