Senate Ratings - Election 2012 - NYTimes.com

In 2010, Linda E. McMahon, a Republican, spent tens of millions of dollars from her own pocket to win a Senate seat in the Nutmeg State, but the former chief executive of World Wrestling Entertainment was trounced by Attorney General Richard Blumenthal. She is back, and her retooled campaign has recast her as a moderate mother and grandmother. Meantime, her Democratic opponent, Representative Christopher S. Murphy, has struggled with name recognition and personal finance questions. In a presidential election year, the state still leans Democratic, but Ms. McMahon is making Democrats pay attention.

Senator Bill Nelson, a Democrat, has all the same worries as any incumbent in a swing state where the economy is suffering and President Obama’s popularity is, too. Representative Connie Mack emerged relatively unscathed from a crowded primary contest on Aug. 14 but has taken fire for past personal antics. Despite a neck-and-neck presidential contest in Florida, Mr. Nelson has shown a consistent lead in the polls.

The retirement of Senator Daniel K. Akaka opens up a reliably Democratic seat. Republicans had a hint of hope after recruiting former Gov. Linda Lingle to run. But winning election in a Democratic state, with President Obama at the top of the ticket, will be difficult. Rep. Mazie K. Hirono is the Democratic nominee, chosen after a relatively bloodless primary and with solid backing of national Democrats who saw her as their strongest candidate.

On paper, things should be glum for Debbie Stabenow, the two-term Democratic senator here. The Michigan economy is among the worst in the nation, and Ms. Stabenow is closely associated with President Obama. But the bailout of the auto industry, derided in many other states, is not a negative for this senator, and both her potential Republican rivals, former Representative Pete Hoekstra and Clark Durant, a charter school executive, have so far failed to light a fire.

When Senator Jeff Bingaman, a five-term Democrat, decided to retire, it opened up a seat that his party fully intends to hold. Democrats have a strong voter registration edge in the state, and President Obama cleaned up there in 2008. After primary fights, Representative Martin Heinrich emerged as the Democratic nominee. Republicans got a good candidate in former Representative Heather A. Wilson, who projects a moderate image. But the environment so favors Democrats that national Republicans are shifting resources elsewhere.

Senator Sherrod Brown, a first-term Democrat, is known as a scrappy and energetic campaigner and will need to stay that way to beat back his Republican challenger, Josh Mandel, the state treasurer and a former Marine. Mr. Mandel is a proven fund-raiser with a strong biography in one of the nation's leading swing states. But Mr. Brown, buoyed by voters' recent rejection of a law that restricted public workers’ rights to bargain collectively, leads this race for now.

Republicans would love to take out Senator Bob Casey, and are hoping President Obama’s poor poll numbers here and the electorate’s chameleon voting habits here will combine to make that happen. But Mr. Casey is more popular in the state than the president, and his moderate ways, rejection of abortion rights and appeal with blue-collar voters will make this an uphill fight for Republicans. A large field of less-than-stellar candidates further hurts Republicans here.

When the state treasurer, Richard Mourdock, emerged victorious from his primary campaign against the longtime Republican Senator Richard G. Lugar, he was hailed as the Tea Party's next hero. Democrats saw something else: the Tea Party's next victim. That may have been proven with his now-infamous comments that "when life begins in that horrible situation of rape, that it is something that God intended to happen." Representative Joe Donnelly, a Democrat, had put himself forward as a moderate combating a conservative ideologue, positioning himself well to take advantage of Mr. Mourdock's rape statement. The contest is now a tossup.

With the surprise retirement of Senator Olympia Snowe, the moderate Republican, Democrats feel better about their chances in Maine – but not because of their own party’s candidate. Former Gov. Angus King, an independent, overshadowed the race when he declared his candidacy and is the presumed front-runner in the three-way race. Control of the Senate could hinge on Maine. While it is widely believed he will caucus with Democrats if he becomes the senator, Mr. King has made no commitments and issued a warning to both parties: “I will take note of how I’m treated in this campaign.”

Senator Scott P. Brown, a Republican, stunned the political class two years ago when he won a special election to fill the seat of the late Senator Edward M. Kennedy. His re-election bid is a critical piece of the Republican plan to win control of the Senate. He faces a strong challenge from Elizabeth Warren, a Harvard professor, who became a champion to Democrats when she set up the Consumer Financial Protection Bureau in the Obama administration.

Senator Claire McCaskill is among the most endangered Senate Democrats this year, struggling to hold on to support in an increasingly conservative state and a starkly different climate than in 2006, when her victory helped the Democratic Party sweep control of Congress. She faces Representative Todd Akin, who has faced criticism for comments he made in an interview about what he called “legitimate rape” and abortion, prompting calls from leaders in his own party to step aside. Though Ms. McCaskill's campaign has benefited from her opponent’s woes, she still faces a tough race during which she will continue to be linked to President Obama, who is not popular in the state. There also is still a chance that Mr. Akin could reverse course and be replaced by a more formidable challenger.

Senator Jon Tester, a Democrat, managed to narrowly win his 2006 race in a state where Democratic candidates for president rarely win. Mr. Tester, a rancher, has leveraged his just-folks image and occasional voting independence into a strong brand. He hopes that will encourage voters who pull the lever for a Republican presidential candidate to swing over to him when it is time to make a Senate choice instead of choosing his Republican opponent, Representative Denny Rehberg.

When John Ensign, the disgraced Republican Senator, resigned earlier this year, Republicans moved quickly to install Representative Dean Heller in his stead, hoping to give him a jump start for 2012. His competition will be a fellow House member, Democrat Shelley Berkley. Party registration favors Ms. Berkley, who hails from Clark County, but she is under a Congressional ethics investigation that could complicate her path. Still, Nevada's ailing economy and its swing-state status combine to make this race a tossup.

The retirement of Senator Jim Webb, a Democrat, has set the stage for one of the year’s most spirited races. Recent population shifts have turned the state into a presidential battleground. President Obama and his policies will be a central component of the Senate race, too, since the Democratic candidate, former Gov. Tim Kaine, led the Democratic National Committee under Mr. Obama. The Republican contender, former Senator George Allen, is seeking vindication after a 2006 re-election defeat.

The retirement of Senator Herb Kohl, a four-term Democrat, creates a wide-open race in a state whose politics are deeply divided. The effort to recall Gov. Scott Walker, a Republican, failed but took attention away from the party’s competitive Senate contest. Representative Tammy Baldwin, the Democratic candidate, is running strong against Tommy Thompson, a former Republican governor, who has struggled to gain ground and replenish his coffers after winning a competitive primary last month. With a tight presidential race here, this contest appears to be a tossup.

The retirement of Senator Jon Kyl, a Republican, has given his party one more open seat to try to hold in its quest to win the majority. Representative Jeff Flake, a well-known and well-established Republican, easily won the Republican primary in August, but not until he was forced to spend millions of dollars in precious resources against his well-financed opponent, Wil Cardon. Democrats got their dream candidate, Richard H. Carmona, a former surgeon general in the Bush administration, a Vietnam war hero and boot-straps Hispanic. But in a presidential election year, Dr. Carmona has to prove he's a contender in a Republican state.

Republicans gained an advantage in taking over this seat when Senator Ben Nelson, the two-term Democratic incumbent, decided not to run again. The Democrats recruited Bob Kerrey, the state’s former governor and two-term senator who returned to his native Nebraska after a decade in New York City. State Senator Deb Fischer emerged as the Republican nominee after winning a three-way primary. The state’s conservative leanings make it a likely, though not sure-fire, win for Republicans.

With the retirement of Senator Kent Conrad, a Democrat, Republicans have a strong chance of taking back this seat in the Republican-heavy state, and are counting it among their must-wins. Democrats are excited about the entry of former state attorney general Heidi Heitkamp into the race. But she hasn’t won an election in years, and Democratic presidential candidates have failed in the state for a generation. And so the race for now seems Representative Rick Berg's to lose.