Much has already been written about the influence of outside spending on this election cycle. One could make a compelling argument that in 2010 super PACs were undervalued, especially by Democrats. Conversely, one could argue that in 2012 the impact of these groups was overestimated, this time to the detriment of Republicans.

So how much impact do they have? The truth is somewhere in the middle. Like it or not, these groups have an important role, but campaigns still begin and end with the candidate’s ability to communicate a compelling vision to voters. Over the last 18 months, I think super PACs did what should be expected of them. They played a supporting role, pushed narratives, gave cover to candidates, and in some cases nudged the needle a point or two in select states and races.

It just so happened that Democratic groups did a better job of this than Republicans. Here’s why.

The early narrative is more important than the October surprise.

Whether he was identifying corporations as people, joking about being unemployed, dismissing $374,000 in speaking fees as “not very much,” or writing off half the country as unable to take personal responsibility for their lives, Mitt Romney proved time and again that he was woefully out of touch with the middle class.

Most of those examples happened in the winter and spring of 2012, when many swing voters were still forming their opinions. The ability of Democratic groups to define Romney (with his help) early on was key to Tuesday night’s victory. For all the money conservative groups spent attacking President Obama, groups like Priorities USA and their work defining Romney’s business record early on stood out as some of the hardest-hitting and most effective messaging of the campaign.

Candidates matter; specifically, nominating ones who don’t talk about rape.

I’d have assumed that after 2010, Republicans learned a lesson: that nominating extremists can cost them a chance at majority control of the Senate. But in Indiana, Richard Mourdock, who said he believes that pregnancy from rape is “something that God intended to happen,” beat statesman Dick Lugar in a primary. And in Missouri, Rep. Todd Akin felt compelled to enlighten us about the female body’s ability to “shut that whole thing down” if it’s a “legitimate rape.”

While no strategist could have predicted that a Republican candidate would utter such outrageous statements, a cursory look at their past could have told you they were bad accidents waiting to happen. My organization understood that, as did Majority PAC, which led the charge on Senate campaigns. I’m pretty sure the Democratic Senatorial Campaign Committee, Sen. Claire McCaskill, and Rep. Joe Donnelly all understood that as well. It seems the only folks who didn’t were the two people responsible for the election of Senate Republicans: National Republican Senatorial Committee chairman John Cornyn and Minority Leader Mitch McConnell.

There’s a better super-PAC model out there.

For all the money Democratic groups were up against, I believe we were more efficient in our spending, more effective in our messaging, and worked better together than our Republican counterparts. American Bridge’s role was to centralize opposition research and candidate tracking under one roof, eliminating duplication among groups and providing those groups with the knowledge they would need to run their polling, advertising, and direct voter programs. Priorities USA, Majority PAC, and House Majority PAC each had clearly defined roles, running ads in the presidential, Senate, and House races, respectively, and progressive organizations like Emily’s List and the League of Conservation Voters, as well as labor unions, all made immeasurable contributions in races across the country. It was good to know that in one of the biggest political fights in recent memory, we were all singing off the same song sheet.

Ninety percent of life is just showing up.

In 2010, Republicans took advantage of the Citizens United decision to sway elections, while most Democrats were reluctant to operate under a system they did not agree with. But the disastrous results of those midterm elections demonstrated that we had to play by the rules as they existed, not as we wished they were. So we participated. And while we knew we’d be outspent, Democrats also knew that as long as we could stay competitive, we could stem and even turn back the tide of conservative outside money.

I recognize that many people in the progressive community would prefer that super PACs did not exist. I happen to be one of them. However, I believe that the outcomes of 2010 and 2012 show that the presence of Democratic outside groups can make a difference and that we only hurt ourselves by unilaterally disarming. So until Congress puts me and my staff out of work by passing sensible campaign-finance reforms, American Bridge will continue our work to support Democratic candidates in 2013, 2014, and beyond.