Why August Will Determine Senate Control

August is usually a sleepy month in politics. Congress leaves Washington for its annual summer recess, and campaigning takes a back seat as voters, more concerned with their own vacations than with statewide elections, tune out. But that’s not the case this year. When the 113th Congress gavels into session in January, the party that controls the Senate will credit key primaries this month with handing them power.

The stakes are high for Republicans. Four states with competitive races hold GOP primaries over the next four weeks. And while the tone of a primary campaign rarely dictates the outcome in the fall, the candidates who emerge from those primaries will either help or hinder their party's chances to win the four seats necessary to take over the upper chamber.

That makes the Republican primaries in Wisconsin, Missouri, Connecticut, and Arizona worth watching.

Sen. Claire McCaskill of Missouri remains the most vulnerable Democrat seeking reelection this year. A recent St. Louis Post-Dispatch survey showed her trailing all three of her possible competitors -- Rep. Todd Akin, businessman John Brunner, and former state Treasurer Sarah Steelman -- between 5 and 11 percentage points. In the same poll, more Missourians said they view McCaskill unfavorably than favorably, highlighting her vulnerability.

McCaskill caught the perfect wave in 2006, when she knocked off incumbent Republican Jim Talent. She had served as the state auditor, which gave her the chance to cast herself as an outsider bent on reforming government. And she ran at a time when voters were upset with the country’s direction. Exit polls showed a majority of voters disapproving of the job President George W. Bush was doing and of the war in Iraq.

Everything that worked for McCaskill then is working against her now. She’s the incumbent, one who cast tough votes for health care reform legislation, the economic stimulus, and the Troubled Asset Relief Program. President Obama is unpopular in the state, and while some Democrats have run away from the top of the ticket, McCaskill has openly embraced him and urged him to run a campaign in Missouri.

(RELATED: A History of Senate Partisan Turnovers)

It’s clear that Democrats want to face Akin. McCaskill’s team recently launched a barrage of negative advertisements against all three Republicans, but the spot targeting Akin might as well have been a positive. It labeled him the “most conservative” candidate and the most committed to small government -- hardly negatives in a GOP primary. Republicans say the Akin ad is airing more frequently than the others, although McCaskill’s campaign won't comment on the ad strategy.

But the same survey that showed McCaskill trailing has Brunner leading the GOP race. He has already put $7 million of his own money into the contest, and he’s hinted at a willingness to spend more. If McCaskill faces Brunner in the fall, Democrats are quietly pessimistic about her chances. Still, she is popular within the Senate Democratic Caucus, and her decision to run six years ago was the party’s first big recruiting win. Those warm feelings and happy nostalgia mean that the party is likely to fight to the end, even if McCaskill’s odds get longer.

Wisconsin’s primary also features a longtime elected official vying to stave off an insurgent with no electoral experience. But former Republican Gov. Tommy Thompson is no Todd Akin. Thompson won election to four terms, and virtually every voter in the state still recognizes him. That makes the fact that Thompson appears to have a hard ceiling on his support perplexing on its face. He hasn’t been above 40 percent in any public poll this year.

Meanwhile, businessman Eric Hovde is playing the role Brunner fills in Missouri, spending heavily from his bank account to introduce himself to primary voters. Republicans see in Hovde many of the same traits that businessman Ron Johnson brought to his race in 2010, when he defeated Democratic Sen. Russell Feingold. Hovde has an interesting populist, anti-Wall Street streak that could appeal to voters angry at an economic meltdown brought on by the financial crisis, although some Republicans worry that he could be defined as the Washington hedge-fund manager, the career that made his fortune.

Most Democrats want to face former Rep. Mark Neumann, whom they see as the most beatable candidate, and some recent polls are showing him surging. But most strategists on both sides believe that the Aug. 14 primary will come down to Hovde and Thompson, with the newcomer edging out the old-timer. Democratic voters remember casting ballots for Thompson during his tenure as governor, but Wisconsin’s Republican electorate has become much more conservative, leading most observers to give Hovde the advantage.

Waiting in the wings is Rep. Tammy Baldwin. The Democrat is easily cast as a Madison liberal who couldn’t possibly win statewide, but Wisconsin Republicans caution against underestimating her. For one thing, Madison Democrats have a much easier time winning statewide elections than do Milwaukee Democrats. (Feingold and former Gov. Jim Doyle both came from Madison, while the current mayor of Milwaukee has lost two bids for the governorship.) Moreover, Wisconsinites have a century-long tradition of electing liberal senators such as Robert La Follette, William Proxmire, Feingold, and Herb Kohl, whose seat is now open.

Wisconsin’s electorate becomes more liberal in presidential election years, although this year’s gubernatorial recall gave both sides the opportunity to build a top-notch field operation. Baldwin will benefit from a stronger turnout in Milwaukee, while the eventual Republican winner will get a boost from suburban Waukesha County, which helped Gov. Scott Walker keep his job.

Two questions will determine the general-election outcome: Can Republicans peel off conservative, out-state Democrats who aren’t predisposed toward a Madison liberal, or will Baldwin unite the Democratic coalition? And which Republican -- all of whom have their faults -- will win in two weeks?

Connecticut and Arizona are less-competitive states, but both could be vulnerable to late surges if a national wave develops -- with the right candidates.

In Connecticut, former World Wrestling Entertainment executive Linda McMahon is again spending millions for her own cause, but Republicans might be better served by choosing former Rep. Christopher Shays. McMahon couldn’t win in 2010, despite the friendly electoral environment and a big financial advantage over Democrat Richard Blumenthal. But Shays is running a seriously underfunded campaign, and McMahon is likely to cruise in the Aug. 14 primary.

Arizona Republicans will choose between Rep. Jeff Flake and businessman Wil Cardon on Aug. 28. Flake is the front-runner, but Cardon has spent more on television advertising, and he’s been closing the gap. Democrats will rely on former Surgeon General Richard Carmona, aiming to take advantage of the state’s surging Hispanic population. Carmona will need a wave that favors Democrats, but he would have a better shot if Cardon overtakes Flake in the primary.

The number of Democratic seats in play jeopardizes the party’s Senate majority this year, but thanks to Democrats' active recruiting in key races, and a few breaks they’ve caught, they are blunting the Republicans' advantage. This month’s primaries will offer the last opportunities for one side to pad its edge, making even traditionally sleepy August a busy time in this nonstop election season.