Next Tuesday, Republican primary voters will nominate a candidate to face Sen. Claire McCaskill (D-Mo.) in the general election. And in the weeks leading up to Election Day, Democratic groups have taken a keen interest in the GOP race, with an apparent eye to helping along the candidate they perceive as the least formidable general election foe.

The latest example is a new radio ad paid for by the Democratic Senatorial Campaign Committee that attacks Rep. Todd Akin (R), but does so slyly, in a manner that appears to be designed to endear him to conservative voters.

Democrats are trying to elevate Todd Akin. (Jeff Roberson/AP)

Bachmann and Huckabee are popular among conservative voters and are from states in the same geographic region as Missouri. If anything, many undecided conservative primary voters who hear their names in the radio ad would be tempted to give him a closer look.

So why do Democrats appear eager to run against Akin? For starters, he is, as the Democratic ad says, very conservative. His nomination would open up the middle for McCaskill in a general election matchup. Secondly, he is unpredictable. Late last year, he shook up his campaign staff. And earlier this week he released a head-scratching and jumbled campaign ad.

The new DSCC ad is notable because it’s the third instance in which a major Democratic player has appeared to try shape the outcome of the GOP contest. McCaskill released a round of three negative ads last month that stood out because the anti-Akin ad, unlike the spots running against businessman John Brunner and former state Treasurer Sarah Steelman, cast the congressman as a “a crusader against bigger government.” Before McCaskill’s ad, the Democratic-aligned Majority PAC released an ad hitting Brunner.

Democrats maintain that their efforts are as much about the general election as the primary and that they cannot afford to sit on the sidelines and abstain from defining their potential opponents.

“Just like all the Republican Senate hopefuls in this race, Todd Akin’s agenda is too right wing and out of touch with Missouri’s middle class,” said DSCC spokesman Matt Canter. “We are going to make sure Missouri voters understand the stark choice between Claire McCaskill and the extreme partisan ideology of whoever wins the Republican primary.”

But taken together, the nuance of McCaskill’s anti-Akin ad, the DSCC’s decision to focus on the congressman, and Majority PAC’s anti-Brunner spot suggest Democratic strategists believe there is utility in trying to influence the outcome of the primary.

According to a Republican strategist tracking ad buys in the race, McCaskill’s campaign and Majority PAC have each spent about $850,000 on ads during the last two and a half weeks – more than Akin has spent on commercials during the entire campaign. So if Akin wins the primary, he might be able to credit some very unlikely allies. And his campaign cautions that it would be a mistake for Democrats to underestimate him.

“The suggestion that McCaskill would prefer to run against Akin would be a very unwise choice on her part,” said Akin spokesman Ryan Hite. “Todd presents the clearest contrast and biggest difference in voting record to McCaskill.”

Whomever McCaskill faces, the fall reelection campaign will be an uphill climb, especially since it is taking place in a state Mitt Romney is favored to win at the presidential level. A recent St. Louis Post-Dispatch/News 4 poll conducted by Mason Dixon Polling & Research Inc. showed the senator trailing all three Republicans, with Brunner holding the largest lead.

Three-way races are hard to predict. Brunner’s personal money, Steelman’s surrogate support (Sarah Palin is campaigning with her today) and the Democratic input could trigger an unexpected outcome next week. But one thing is for sure: Republicans are not going to be the only ones watching the returns once the polls close.