In Nevada, Republicans are battling for what could be the biggest prize for them, the chance to take on Senate Majority Leader Harry Reid and unseat the second Democratic Senate party leader in six years.
What started off as a shoe-string campaign for Tea Party favorite Sharron Angle has morphed into a million-dollar push to derail Sue Lowden, the former state GOP chair favored by the state's Republican establishment.
The former assemblywoman's anti-tax, anti-government message has pushed her up in polls and neck-and-neck against Lowden. The conservative group Tea Party Express has poured half a million dollars into Angle's campaign. Other conservative groups, including the Club for Growth, have also spent hundreds of thousands on Angle's behalf.
2010 Elections Map: Follow the Senate, House and Governors' Races
Angle is an anti-tax crusader and an uncompromising conservative. She favors abolishing the Departments of Education and Energy, phasing out Social Security and Medicare, and taking the United States out of the U.N.
In an interview late last month with The Reno Gazette-Journal, Angle suggested that there could be a violent confrontation because people are so angry with the government, and that the country is under attack.
"What is a little bit disconcerting and concerning is the inability for sporting goods stores to keep ammunition in stock," she told the newspaper. "That tells me the nation is arming. What are they arming for if it isn't that they are so distrustful of their government? They're afraid they'll have to fight for their liberty in more Second Amendment kinds of ways?
"That's why I look at this as almost an imperative. If we don't win at the ballot box, what will be the next step?"
Lowden, a more moderate Republican, has attempted to upset Angle's campaign by linking her to the Church of Scientology and questioning her campaign finance tactics, but the Tea Party favorite continues to inch up in polls.
Reid's supporters are thrilled with Angle's success and are convinced that her outside-the-mainstream views make her the easiest Republican to beat in the general election.
Independents make up about 15 percent of voters in Nevada, and even some Republicans are concerned that Angle won't be able to attract those votes if she's up against Reid in November. Polls have shown that Reid would face a tougher fight if he's facing Lowden in November.
The last Senate Democratic party leader to be defeated for reelection was South Dakota's Tom Daschle, who lost the election, and his position as minority leader in 2004 to Republican John Thune.
Reid may be in for the toughest political battle of his career as Americans' anti-incumbency sentiment peaks to a new high and satisfaction with members of Congress drops to a new low, according to a new ABC News index measuring Americans' pent-up discontent.
ABC News' new Frustration Index stands at 67, higher than the estimated level of 63 in 1994 when Democrats lost Congress and the GOP regained control of Congress, and in 2006 when Democrats took it back. In contrast, a lower Frustration Index has been favorable to incumbents. In 1998, when the estimated Frustration Index stood at 39, the reelection rate for incumbents was 98 percent.
Primary Day in 12 States
Incumbents across the country are feeling the heat from voters. Like Reid, Arkansas' Democratic Sen. Blanche Lincoln may be facing the toughest political fight of her political career.
Lincoln will face off against Lt. Gov. Bill Halter in a runoff primary today, and if she loses, she will become the third U.S. incumbent senator to be voted out, after Sen. Arlen Specter, D-Pennsylvania, and Sen. Bob Bennett, R-Utah.
No more than one U.S. senator has lost a primary since the 1980 election, when four incumbents were defeated in intraparty fights.
In the May 18 primary, Lincoln didn't get the 50 percent of votes needed to win the Democratic seat outright, pitting her once again against Halter, whose received millions of dollars from labor unions opposing Lincoln.
Both President Obama and former president Bill Clinton have endorsed Lincoln, but voter discontent with incumbents remains high in Arkansas.
Republicans Take Center Stage in California
Republican women are leading in California, where former Hewlett-Packard chief executive Carly Fiorina has a substantial lead in the Senate primary, and former Ebay chief executive Meg Whitman is leading the race in the gubernatorial nomination.
Whitman spent more than $70 million of her money in her campaign to succeed Gov. Arnold Schwarzenegger, a moderate Republican.
In South Carolina, adultery allegations don't seem to have hurt gubernatorial candidate Nikki Haley, who still has a double digit lead in her race.