With Mitt Romney the defacto winner of the Republican presidential nomination, many have argued that the influence of the Tea Party is on the wane. But at a local level, the movement is having a real impact, with moderate Republicans coming under huge pressure from the Right.
"Even though the Tea Party has brought a lot of good things to the Republicans as far as energising the base [is concerned], there has been a little bit of a downside to it and I'd say potentially losing Richard Lugar who is the most experienced Republican in the Senate ... knocking him out in the Primary process is going to be harmful to the Republicans overall in Washington."
- J.D.Gordon, a former spokesman for Herman Cain
Richard Lugar, a moderate Republican senator from Indiana, who has served 36 years in the US Senate, has become the latest victim of the Tea Party movement and SuperPac spending.
Lugar's opponents spent an estimated $3m on the campaign against him - highlighting his willingness to reach across the aisle and compromise with Democrats.
On Tuesday, Lugar lost the fight for his political life as state treasurer Richard Murdouck, his Tea Party-backed challenger, defeated him in the Indiana primary for the Republican nomination. It is a victory which some suggest is a significant scalp for the Tea Party movement, which first emerged in 2009, shortly after Barack Obama took office.
Those who identify with the movement are generally opposed to high taxes and want to reduce government spending. They opposed the stimulus package and bank bailouts - in short, they want a smaller government.
In 2010, Tea Party candidates scored a number of political victories in the mid-term elections, which saw the Republicans reclaim the House of Representatives.
But there were some high-profile failures as Tea Party candidates in Nevada, Delaware and Alaska won primary victories but failed to garner enough support to win the general election.
"It's been the Tea Party's mission to hold Republicans primarily to account."
- Anne Kornblut, Deputy political editor, Washington Post
So how popular is the Tea Party movement nationally?
A recent poll found that 41 per cent of Americans identify themselves as supporters of the Tea Party and 45 per cent oppose it. Among Republicans, 74 per cent say they support the Tea Party.
So are we witnessing the resurgence of the Tea Party and will the movement be influential in the US presidential elections this November? And what does the race tell us about the state of the Republican Party? Does it suggest there is no longer a place for moderate Republicans in Congress?
Inside Story: US 2012, with presenter Shihab Rattansi, discusses with guests: Andrew Langer, a Tea Party activist and president of the Institute for Liberty, a conservative, non-profit advocacy organisation; Anne Kornblut, the deputy political editor of the Washington Post who has covered the Tea Party movement; and J.D. Gordon, a former spokesperson for the Herman Cain presidential campaign.
"[The] Tea Party came into being in reaction to the massive level of spending that President Obama put in in 2009. So in the 2010 election you saw that Tea Party reaction not just in the demonstrations early in the year but then in elections. So about 80 Tea Party guys got elected to the House and the Senate so they didn't go away, they came to Washington. They started governing, they stopped the president from raising taxes."
Grover Norquist, the founder of Americans for Tax Reform