Howard Baker was an R but also Everett Dirksen’s son-in- law. Dirkson was R minority leader but did not like Nixon (who did?). Smiling Sen. Sam Ervin (country lawyer) also played a big role. As did Peter Rodino who as totally partisan D as he was, acting like a Judge at the Nuremberg trials so prim and proper.
Nixon had also turned off a large portion of his base (footsies with China etc) so the R’s did not truly pr totally support him.
Obama has also told much of his base to “fly a kite - what are you gonna do? Not vote for me? Sue me!”
No, Obama is definitely vulnerable BUT (a) where is the Democrat who will step forward and throw the first stone? (Kucinich is gone)and (b) how would we avoid the African American backlash?