Even before the Republican takeover of Congress, conservative Democratic collaborators gave Republicans effective Congressional control for many years. Compare where we were in 1980 to where we were when Clinton first took office, in terms of most subjects of general debate between the parties. Tax levels? In 1980, the top bracket paid 70%. In 1992, it was just 31%... well under half the previous level. Or look at military spending. In 1980, we spent $134 billion on our military. By 1992, we spent $298 billion. That's nearly a 1/3 increase even AFTER accounting for inflation, despite 1992 being after the end of the Cold War, whereas 1980 was the depth of the Brezhnev regime. In what way was the period from 1980 to 1992 NOT an era of growing federal policy conservatism? It was a time known for deregulation (leading, for example, to the S&L meltdown), and no meaningful gun control, and the stacking of the courts with Republicans (7 Republicans to only 2 Democrats by 1992), and federal non-military spending growth rates well below historical norms, etcetera. If you were merely given the budget from 1980 to 1992 and asked to guess which party controlled the Congress in those years, you'd wrongly guess the Republicans controlled both houses, because they were getting almost anything they wanted.
Conservative ideas have been tried repeatedly. They were tried under three consecutive Republican presidents leading up to the Great Depression. They were tried during the Reagan/Bush years, leading to higher poverty, an all-time record for the violent crime, teen pregnancy, and divorce rates, and below-normal GDP growth and job creation, and they were tried during the GW Bush years, leading to a catastrophe surpassed only by the Great Depression. Liberal policies have been tried, too. During the FDR/Truman and Kennedy/Johnson years, we have very meaningful liberal legislative sucesses.... and, to a much lesser extent, we had some serious liberal policymaking in Clinton's and Obama's first couple years. Those periods of liberal policymaking were generally followed by excellent socioeconomic results.
Bush failed to regulate the explosion of exotic financial derivatives, he ran up lots of economically ineffectual debt on the Iraq War, and he cut taxes for the super-rich, while neglecting the interests of the poor and middle class, resulting in an erosion of our broad economic base.
Here's the funny thing about conservatives. For eight long years, those of us on the left warned, at every step of the way, that there would be serious negative consequences for the policies Bush was pushing. Then, when things did, indeed, go to hell in a handbasket, the conservatives acedt like nobody could have seen this coming, and nobody could point to anything that Bush did wrong to cause the problems. We told you his policies were horrible all along. You ignored it. Ever wonder why every time your ideas get tried the results are bad?