Victories by Tea Party-backed Republicans made certain the conservative movement will have a front-row seat in Washington to do battle for cuts in government spending and deficits.
But at the same time, their presence may make it harder for Republicans and Democrats to find middle ground on the main issues of the day and would likely lead to more gridlock.
Waving the Tea Party banner were Republicans Marco Rubio of Florida and Rand Paul of Kentucky as they rolled to victory in their Senate races.
Others were not able to make it, such as Republican Christine O'Donnell, backed by Tea Party champion Sarah Palin.
O'Donnell defeated moderate Republican Mike Castle to win her party's nomination, but lost the Delaware Senate race to Democrat Chris Coons.
The Tea Party is a new phenomenon in American politics, a loose-knit group of people outraged by government spending, rising debt and deficits, and President Barack Obama's healthcare overhaul.
Democrats have tried to portray them as political extremists, pointing to their calls to privatise Social Security and to Paul's complaints that the Federal Reserve Board has too much power over the US economy.
Paul has been a strong critic of the power of the Fed and his election could herald a push by on the right flank of the Republican party to tighten Fed oversight.
Republicans have largely welcomed the Tea Party representatives, feeling they were pressing the same issues and fretting that to do otherwise risked splitting the Republican Party right down the middle. "We know they're focused on the same things that we are -- reducing wasteful spending, reducing debt, repealing or replacing healthcare," said Don Stewart, spokesman for Senate Repub-lican leader Mitch McConnell. "We're all pointed in the same direction on that front."
But the Tea Party movement may give Obama a foil to attack as he adjusts to the new political reality in Washington.
Some in the movement support such dramatic gestures as eliminating the departments of Energy and Education as a way to save money and reduce government's influence in Americans' lives, and those ideas are unlikely to be embraced.
McConnell and the House Republican leader John Boehner will face the dilemma of making sure the Tea Party is a positive force within the party and not one that is a harmful distraction as Republicans seek bigger gains in Congress in 2012 and attempt to deny Obama a second term.