The only possible good that can come of this wretched campaign is the ever-increasing likelihood that it will cause the Democratic Party to self-destruct. A lot of people are seriously worried about this, but I am not one of them. I have never been much of a Party Man myself. . . and the more I learn about the realities of national politics, the more I’m convinced that the Democratic Party is an atavistic endeavor – more an Obstacle than a Vehicle – and that there is really no hope of accomplishing anything genuinely new or different in American politics until the Democratic Party is done away with.
From Fear and Loathing on the Campaign Trail '72
if you mean when they switched being liberal/conservative, this was well after that
yes, thank you
if it helps;
FDR began the process in the 1930s with his response to the Great Depression. Conservative funders fled to the Republicans, although they remained a relatively minor voice until they were able to capitalize on the racist backlash to the Civil Rights movement in the 1960s.