It's now almost three years since the day CNBC reporter Rick Santelli threatened during a live broadcast to begin dumping derivative securities into Lake Michigan and start a Chicago tea party.

That one act of broadcast petulance sparked a viral grass roots movement that captivated parts of the Republican right and swept through those febrile, anxiety tinged, partisan corners of cable TV and the internet faster than Sarah Palin can drop a moose.

Within a few months this new social movement had captured the interest of an estimated 30 per cent of the American voting public.

Rallies and bus tours spread across the country and demonstrators in colourful historic costumes poured into Washington to rage against the Socialist in the White House who was apparently determined to undermine American exceptionalism, defy the constitution and turn the country into France.

By the mid-term elections the Tea Party had claimed credit for one of the biggest turnarounds in the House of Representatives ever seen.

Sixty seats lost by Democrats to the Republicans – bigger than the gain of 54 seats made against the Clinton Democrats in 1994 and a swing not seen since the Democrats took 75 seats from the Republicans in 1948. But three years on it seems the steam is starting to come off the party.

The latest polling suggests that Tea Party support has dropped to around 25 per cent in those districts represented by the group in congress that calls itself the Tea Party Caucus and many might be starting to wonder what the movement – if that's what it is – has actually achieved.

The very people who promised to shake up Washington have instead been one of the main reasons the last year in congress was the most futile legislative year on record. Last year congress passed just 80 bills – less than any other session since records began in 1947.

Compromise is not part of the Tea Party platform. The new candidates spent a good deal of time and energy threatening to shut down government and fuming about an increase in the debt ceiling that if not granted would have spooked the markets at the very least. However unlikely, their threats had almost everyone talking about the possibility of the country being dragged toward default. Of course neither happened in the end, but the stonewalling and foot stamping only contributed to the distaste most Americans now have about their political process. Congress is more unpopular than it's ever been and the Tea Party-backed candidates are now in danger of being seen to belong to the political establishment.

For all that the Tea Party Caucus and their followers in the numerous small town 'New Republic Patriot' groups might like to think they had actually pulled the Republican party further toward their small government, low tax, libertarian agenda, the Republican party itself looks almost certain now to elect the most moderate establishment candidate to go up against Barack Obama later this year.

Mitt Romney, the man Newt Gingrich derides as 'that Massachusetts moderate' who has flipped and flopped on red meat conservative issues like abortion and gay marriage and who, as Massachusetts governor, introduced what is essentially the prototype for the Obama health care law; the one piece of policy that is the biggest target of all for those who got on board the freedom express busses to Washington to march in the streets and pledge to 'take back America'.

With Mitt Romney now holding a significant lead in the polling for the latest primary in South Carolina, the local Tea Party leaders have urged their followers to fall behind one candidate other than Romney otherwise - as one poster put it - 'Romney will win the nomination and Obama will win…(the presidential election in November)'.

That's certainly the line Newt Gingrich is pushing as he continues in his increasingly vain effort to unseat the front runner.

The super PAC that's supporting him and spending millions on an anti Romney campaign in South Carolina this week released an advertisement that declares outright that 'Mitt Romney is not conservative and not electable'.

Gingrich and the Tea Party leadership may be right, there are plenty of people on either side of the political fence who believe you can't defeat an incumbent president by playing safe. And as conservative commentator Mark Steyn put it:

Mitt Romney looks like a 1950's department store mannequin… he doesn't frighten the horses but Ronald Reagan didn't take out Jimmy Carter by being cautious and Clinton didn't take out George Bush Snr by being cautious and Mitt Romney is a very safe guy.

But, that aside, an Obama victory might be the one thing that would bring back the steam and keep the Tea Party alive.

Michael Brissenden is the ABC's Washington correspondent. See his full profile here.