The Road to 2020 - American Elections . The GOP hasn't really put the crosshairs on him.
Last election the mudslinging was basically done by other Democrats, Hillary etc. It was convenient for GOP to portray Bernie positively or simple to back off, because he wasn't the "official" candidate. — ssu
Simply untrue. You're a non-American, so I don't expect you to have a strong pulse on American political discourse, but it's simply not true that Bernie has thus far escaped criticism and scrutiny from the GOP.
That Bernie Sanders will be painted to a like Corbyn is evident for examples like this article from Tom Rogan's piece in the Washington Examiner last month: — ssu
Anyone who is an avid reader of the Washington Examiner is unlikely to consider voting for Sanders in the first place. However, the GOP (and the Democrats) have leveraged the state of contemporary Venezuela against Sanders and other Left politicians for the last year, which doesn't stick given that the simple solution, which has in fact been effective, is to ignore it and point to other developed countries or Norwegian models instead, some of which have Governments with larger wealth ownership in their countries than the Venezuela government has over their own.
Sanders has, cynically, been accused of some odd but new strain of anti-Semitism in which criticism of Israel is considered criticism of Jews, but this also won't be effective given that 1) Sanders is obviously Jewish and had relatives killed in the Holocaust, 2) the GOP has their own problems with anti-semitism and 3) Jewish Americans, unlike British Jews, overwhelmingly vote Democrat.
None of these slanders are particularly novel or potent.