Excerpt from a post I made a few minutes ago at Volkh (but which is more relevant here):
"When I worked on the Hill briefly in the 90's, Ron Paul was regarded by many Republicans as almost a folk hero who they wished they could emulate without paying at the ballot box. There was even loose talk amongst some staffers wondering why the LP didn't just fold into the Republican Party. Things have changed so much now, though, that people like Bob Barr and Dick Armey (both poster children for 1990s social conservatism) have joined the libertarian movement, and are now regarded by the Right as whacky leftists. The number of disaffected Republicans who were considered the "establishment" 7 years ago is staggering: Barr, Armey, Christine Whitman, Colin Powell, William Buckley, Bruce Fein, Richard Viguerie, the Chafee family, Bob Smith, Paul O'Neill, Chuck Hagel, Sen. Webb, and dozens more."
While we're at it, we may as well give credit to the original defector, Jim Jeffords, even if he wasn't exactly an "establishment" type at the time. Some others worth adding: George Will (can't believe I left him off the original list) Bruce Bartlett, David Kuo, Andrew Sullivan, Gen. Abizaid, John Dean, Alan Greenspan, Paul Kagan, Matthew Dowd. I would also consider adding Pat Buchanan, Joe Scarborough, and Tucker Carlson. Admittedly, some of these were never necessarily establishment Republicans, but they show the broad spectrum of conservatives, libertarians, and "moderate Republicans" who have suddenly found themselves abandoned by the Republican Party. I would love any additions to this list.
Ultimately, one has to wonder just how many prominent defectors it will take before the remaining Republicans get out of their denial and: 1. stop claiming that the defectors are just "wimps" or "RINOs"; and 2. realize that they've changed the character of the Republican Party from a collection of various types of conservatives and constitutionalists to a group that exists for the sole purpose of expanding the power of the federal government. The good news is that if the remaining establishment doesn't wake up to these facts, a continuing stream of defections will cause the Party to collapse and a new major party to arise from the ashes, much as the Republican Party rose from the ashes of the Whigs.