Republicans gained a symbolic victory in Illinois, nabbing the Senate seat formerly occupied by President Obama, and won in a number of key states as more Democratic incumbents fell prey to voter discontent Tuesday.
GOP candidate Mark Kirk will beat Democratic state treasurer Alexi Giannoulias, according to ABC News projections, in a race that was considered a dead-heat until the very end. Independents have generally voted for the Democratic Senate candidate in previous elections except in 1998. But this year, they went for Kirk by a large margin, 58-29 percent.
President Obama enjoys a 55 percent favorable rating among these voters, one of his best in any state, but 16 percent of those who voted for Obama in 2008 crossed over to Kirk this year.
In Pennsylvania, another Democratic stronghold, Republican candidate Pat Toomey was projected to defeat Democrat Joe Sestak, who beat longtime Sen. Arlen Specter in a bitter battle earlier this year. The poor economy and government dissatisfaction played to Toomey's favor.
Russ Feingold, D-Wis., was projected to become the second Democratic senator to be defeated, after Sen. Blanche Lincoln of Arkansas, who became a casualty earlier Tuesday evening, according to ABC News projections.
There was one bright spot for Democrats on the West Coast, where Sen. Barbara Boxer, another Democrat who ran a tight race against ex-Hewlett Packard chief executive Carly Fiorina, is projected to retain her seat. Senate Majority Leader Harry Reid is also projected to continue in his position despite a bitter battle that nearly put the longtime senator out of office.
Republicans are so far projected to take six seats from the Democrats. In addition to Arkansas, the GOP appears to have scored a key victory in another Democratic stronghold, North Dakota, where Gov. John Hoeven will become the first GOP senator from the state in 24 years. The Republican will replace retiring Sen. Byron Dorgan, a moderate Democrat who has occupied that seat for 18 years.
Across the country: Republicans have so far gained Senate seats in Illinois, Pennsylvania, North Dakota, Arkansas, Indiana and Wisconsin. They've held on to Senate seats in South Dakota, Kansas, Oklahoma, Iowa, Missouri, Louisiana, Ohio, Kentucky, Alabama, Georgia, Florida, South Carolina, North Carolina, New Hampshire, Arizona, Utah and Idaho.
The Tea Party has scored major victories in an election dominated by U.S. economic woes. Republican Marco Rubio will win the Florida Senate race by a wide margin and GOP candidate Rand Paul will win the Kentucky Senate race, according to ABC News exit-poll results.
In Indiana, according to ABC News projections, Tea Party favorite Dan Coats will defeat Democrat Rep. Brad Ellsworth in a race to replace retiring Democratic Sen. Evan Bayh, and incumbent Sen. Jim DeMint will win another term in South Carolina.
"Tonight, there's a Tea Party tidal wave and we're sending a message to" lawmakers in Washington," Paul said in his victory speech. "It's a message on fiscal sanity, it's a message on limited constitutional government and balanced budgets."
Two of the most high-profile races of the election season, however, appeared to be less favorable for the Tea Party. GOP Delaware candidate Christine O' Donnell, who received the most news coverage of the 2010 candidates, will lose to Democrat Chris Coons, ABC News projections show.