One thing I've noticed is how there have been a lot more D to R turncoats than R to D turncoats. But of the few R to D turncoats that I know of, a lot of them happened during the Nixon administration:
1969 - John Lindsay, former Republican congressman and current mayor of New York, loses renomination and is forced to run on the Liberal line. In 1971, he joins the Democratic Party.
1970 - Floyd Haskell, the Speaker of the Colorado House, switches to the democrats. In 1972, he unseats incumbent senator Gordon Allott.
1972 - Ogden Reid, congressman from Westchester County, bolts from the Republicans to the Democrats
1973 - a few weeks into his fourth term, Donald Riegle, a Flint congressman, switches to the Democrats.
Do you think this is a coincidence or do you think that it was mostly Nixon's fault?