Is politics cyclical?

I attended a fascinating class at the Kennedy School yesterday delivered by David Gergen, who talked about the cyclical nature of American politics. Essentially the argument goes something like this:

Although both Democrats and Republicans have occupied the White House over the last couple of hundred years, the political centre of gravity has never strayed too far from the centre. This is because each presidency has been constrained by a prevailing set of ideas and norms, concerning the role and size of the state.

Every once in a while, a rupture occurs to the established order, where the prevailing ideas and norms are challenged. Examples include the radical expansion of the state under FDR in the 1940s (which ended with the 'New Deal') and the "Reagan Revolution" during the 1980s, which sought to radically repeal the power of the state.

Most presidencies though tend to fall within these broad cyclical shifts and therefore either confirm or consolidate prevailing ideas and norms, rather than challenging them. So despite winning power for the Republicans in 1953 President Eisenhower did not fundamentally challenge the prevailing view of the state's role established a decade earlier under FDR. Similarly Bill Clinton, who's presidency interrupted twenty years of steady Republican rule, did not seek to challenge the established conservative consensus established under Reagan. Indeed Clinton is famous for stating "the era of big government is over".

The question now is whether the election of Obama in 2008 represented a break from the established order or whether in fact it was merely a temporary blip in an otherwise conservative-dominated cycle. It is probably too early to say but it is worth nothing the following: although most of the US media have for months dismissed the Tea Party as an extremist fringe of Republican thinking the election of several Tea Party-backed candidates over more established Republican figures and the expected outcome of the mid-terms suggests they are not as far from the political mainstream as has been assumed.

It would be interesting to compare this account with an analysis of recent British political history. Are we still living in an essentially Thatcherite cycle or does the existing coalition government represent a break from the established order? Discuss!