In a year in which control of the U.S. Senate is on the line, the race to fill the Iowa seat being vacated by retiring Democrat Tom Harkin is proving to be one of the keys to the national contest. But there is something else that is being illustrated by the battle between Republican Joni Ernst and Democrat Bruce Braley. The Democrats’ belief that they can repeat their 2012 victories with assertions that the GOP is waging a war on women or is in the pocket of the Koch brothers may be a big mistake.

Heading into 2014, most pundits thought the Democrats were in good position to hold the Iowa seat. But that expectation was based on the notion that Braley was a better candidate than he has proved to be as well as the belief that Republicans would nominate a bland conservative who could be bludgeoned with the Democrats’ favorite tactic: the accusation that Republicans are at war with women. Both assumptions proved to be mistaken.

Braley’s hot-tempered and condescending manner has cost him dearly. So, too, did his gaffe in which he warned a group of fellow trial lawyers that if the GOP won the Senate, the Judiciary Committee would be led by an “Iowa farmer”—Chuck Grassley, the state’s respected senior senator. But his contempt for one of the staples of the state’s economy might not have been as big a deal had he not been opposed by State Senator Joni Ernst. The tough-talking conservative has not only undermined conventional wisdom about the race but also the Democrats’ confidence in their ability to exploit women’s fears to win elections.

Ernst’s easy win in the Republican primary was the first sign of trouble for Democrats. But they hoped that her surge—driven in part by a clever TV ad in which she spoke of her farm girl background and experience in castrating hogs as evidence of how she’ll make the Washington establishment squeal—would be followed by gaffes that would expose her as another Tea Party extremist who would sink in a general-election fight. But if Braley was underestimating his opponent, he soon learned she was more than equal to the test of a competitive statewide race. That was on display in last weekend’s first debate between the two in which Ernst took the Democrat apart in a textbook example of what happens when a well-prepared candidate comes up against one who is still laboring under the delusion that the seat is still his to lose.

That Ernst, a lieutenant colonel in the Iowa National Guard who served in Iraq, is no pushover who could be easily labeled an extremist is something Braley still hasn’t quite come to terms with. Though he attacked her non-stop in the debate, she kept her cool, and counter-attacked effortlessly in a manner that left the congressman fuming. The race was already trending in her direction before the debate as a Des Moines Register poll showed her up by six points over Braley. The next surveys may bring even worse news for the Democrats.

But the point here is not just that Republicans may have lucked their way into finding exactly the right candidate to champion conservative economic positions in a state where liberal populists like Harkin have been popular. It’s that when employed against principled and credible female Republicans, the war on women tactic fails.

It is true that, as last week’s Des Moines Register poll shows, Braley has maintained a big edge among women voters leading Ernst by a 46-33 percent margin. But the gender gap factor hasn’t pushed the race into the Democratic column. Though she trails among women, Ernst leads Braley among male voters by an even more stunning 55-30 differential.

Just as important was the way one of the key moments in the debate undermined the notion that Democratic harping on the contributions of the libertarian Koch brothers will taint anyone they support. When Braley accused Ernst of being in their pocket, she tartly replied that he was dependent on the support of environmentalist billionaire Tom Steyer. Moreover, while Ernst’s conservatism is not in question, Braley’s decision to flip-flop and oppose the Keystone XL Pipeline to win Steyer’s favor makes any talk about the Kochs’ influence so much hypocritical hot air.

Many Republicans believed their 2012 defeat in the presidential election and the disastrous impact of misogynist gaffes like that of Todd Akin on Senate races meant they had to change their positions on religious freedom, ObamaCare, and abortion to win elections. But Ernst’s strong run is once again illustrating the fact that what they needed were candidates who could articulate their principles without shooting themselves in the foot.

While most of the battleground contests in 2014 are in red states, the race in competitive Iowa is a truer test of the Democrats’ reliance on their standard tropes about women and big money. With five weeks to go it’s clear that their reliance on smearing Republicans on women’s issues and the Koch brothers won’t work against Joni Ernst. Instead of trolling the country for bland moderates as some GOP establishment types were recommending a year ago, Iowa demonstrates that what they really need are more tough-as-nails women like Joni Ernst.