I've been pointing out for a while that, while Republicans today claim that President Obama is an unprecedented left-wing radical, and that Bill Clinton was far more moderate, in the 1990s they were just as hysterical about Clinton as they are today about Obama. Andrew Ferguson makes this point better and in much greater detail:

I remember a press conference in 1993 got up by Empower America, a now-forgotten Republican think tank. The purpose was to mark the end of the first year of the Clinton administration. A murderers row of famous-for-Washington conservatives took turns denouncing the Democrats who had seized the White House after a dozen years of Republican benevolence. The upshot of the press conference was tersely summarized by Jack Kemp, a man not known for terseness: President Clinton, Kemp said, had brought to Washington something it had never seen before, the “first frankly left-wing administration in history.” ...
Now it’s 2010, and among his former enemies, Clinton is enjoying a Truman-like renaissance. Even such sweaty anti-Clinton paranoiacs as the investigative journalist Christopher Ruddy and the newspaper proprietor Richard Mellon Scaife have decided he wasn’t so bad after all. It’s almost enough to make you forget the insanity that gripped Clinton’s political opponents. Kemp didn’t know the half of it! Throughout the nineties I heard mainstream Republicans describe the president as a shameless womanizer and a closeted homosexual, a cokehead and a drunk, a wife beater and a wimp, a hick and a Machiavel, a committed pacifist and a reckless militarist who launched unnecessary airstrikes in faraway lands to distract the public’s attention from all of the above.
At gatherings of conservative activists the president was referred to, seriously, as a “Manchurian candidate.” Capitol Hill staffers speculated darkly about the “missing five days” on a trip Clinton had taken to Moscow as a graduate student. Respectable conservatives in the media—William Safire, Robert Novak, Rush Limbaugh—encouraged the suspicion that Clinton’s White House attorney, a manic depressive named Vincent Foster, did not commit suicide, as all available evidence suggested, but had been murdered by parties unknown, to hush up an unspeakable secret from the president’s past.

Ferguson chalks this up to a general, cross-partisan tendency to demonize whoever is currently leading the opposition. I agree that the phenomenon can be found on both sides. But the Democratic version of this style of thought actually reflects reality much more closely.

The Republican party really has been lurching rightward for more than three decades, and the Democratic Party has, somewhat less dramatically, shifted toward the center. The result of this is that Richard Nixon's dometic policies were, in many respects, liberal even by contemporary Democratic standards, and unthinkably left-wing by contemporary Republican standards. Many of Ronald Reagan's biggest and most far-reaching policies -- the 1982 deficit reduction, including the biggest tax hike in American history, or the 1986 Tax Reform Act that ended preferential treatment for capital gains and increased the tax burden on the rich -- would be unthinkable in today's Republican Party. Not only would a Republican president not support them, it's impossible to envision even the least conservative Republican in Congress endorsing such measures.

Meanwhile, Obama's "left-wing" agenda consists of a health care plan based on the 1993 Republican health care plan, and endorsed by past generation Republicans like Bob Dole, a cap-and-trade plan similar to the one John McCain ran on in 2008, and an auto bailout that followed in the policy footsteps of the Bush administration. Obama has kept in place Bill Clinton's moderate positions on welfare and crime, and moved further rightward on guns.

In short, the notion of Obama as representing some radical ideological break is pure hyper-partisan fantasy. But the idea that Republicans keep moving rightward seems well grounded in modern history.