There’s reportedly a joke going around among Iowa Republicans that Marco Rubio must be running for mayor of Ankeny, the Des Moines suburb where his sole Iowa office is located. Defying Iowa’s tradition of retail politics, Rubio also rarely holds campaign events outside of that area and is choosing to invest in television ads over staffers and offices in the state. Rubio is making a deliberate gamble that Iowans will brave the cold on his behalf this Feb. 1 simply because they saw his advertisements or debate performances on television, not because they have seen him in person or heard from his campaign.

The Rubio campaign particularly disdains field offices, the storefronts of retail politics: brick-and-mortar locations where volunteers assemble, local mailings are coordinated and paid staffers work late nights. Deputy campaign manager Rich Beeson has argued that staff can “set up in a Starbucks with wireless and get just as much done.” The tasks that staff and volunteers traditionally perform in these offices — dividing turf for volunteer canvassing, calling prospective voters and distributing information about the candidate — can now be accomplished using online tools without the cost and hassle of setting up a local presence.

Is Rubio right to bet against field offices? Are physical offices relics of a bygone age of retail politics, and is Rubio simply smart to realize it?

According to political science research, Rubio avoids the establishment of a ground game at his peril. Field offices work because they provide a location for the coordination and training that make voter contact valuable. Campaigns that can contact supporters personally to encourage them to vote should make every effort to do so. Knocking on doors can increase turnout by nearly 10 percent, and effective phone calls can encourage an additional 4 percent of voters to head to the polls. Without a field office in an area, candidates will find it much more difficult to translate these tactics into victory.

To be fair, neither canvassing nor phone calls technically require a field office. If a campaign’s main goal is merely to contact as many voters as possible, staff members will often spare themselves the time, effort and cost of training local volunteers by hiring professional callers and recruiting canvassers from out of state. But when campaigns take this shortcut, they often pay the price.

For example, professional callers are paid per call and often tend to read through prompts quickly, with no incentive to start a conversation. These impersonal phone conversations have no demonstrated effect on turnout. If a campaign farms out its calling operation without training the call center workers — admittedly a costly and time-consuming exercise — they are throwing their money away. When well-trained local volunteers make phone calls, they are more likely to connect with voters through a casual discussion. It is more cost-effective to train volunteers, and it is much simpler to conduct phone bank trainings in a field office than in a Starbucks.

When it comes to door knocking, not every visit is equally effective, as the 2004 Howard Dean campaign found out. Dean’s campaign brought in 3,500 out-of-state volunteers for the caucuses instead of building a team of Iowans to talk to Iowans. The kind of people who volunteer for campaigns, especially those who are willing to drive across state lines to canvass, tend to hold extreme views on the issues. They need coaching from campaign staffers if they are to stay on message. Wearing orange caps that read “The Perfect Storm,” Dean’s untrained and untested volunteers were unable to deliver Iowa. The research on this point is clear: If a campaign wants to mobilize voters in a particular area, local volunteers are more effective, and field offices are the best places to train them.

Over the past few presidential elections, field offices have clearly generated higher local turnout. Obama opened 786 field offices in 449 counties in 2012, and each office delivered him approximately an additional 0.3 percent of vote share — or roughly the equivalent of airing 1,000 additional campaign ads. In 2008’s battleground states, Obama earned about 200,000 votes — about 7 percent of his margin of victory in those states — from his network of field offices. These offices accounted for 50 percent of Obama’s margin of victory in Indiana, and they likely made the difference in his win in North Carolina.

These effects seem small, but they make a difference where it matters most. Rick Santorum won the 2012 Iowa caucuses by 0.03 percentage points, or 34 votes out of 121,501. Field offices can be expensive — the estimated cost per vote earned by having a field office is $49.40 — but the earned media and momentum benefits from a victory in Iowa are huge.

Assuming a per-ad cost equal to the average rate paid by the Obama campaign in October 2012, it cost $672,446 to earn the same increase in vote share using ads as by opening a new field office — which costs only about $21,000 to operate throughout an election season. In spite of this evidence, Rubio and his super PAC allies have made a $10.6 million bet on TV ads, while Ted Cruz and Donald Trump have spent less than a million combined on the airwaves.

Campaigns that choose to leave effective field tactics on the table are making a mistake. Field offices provide the training and coordination that make the most effective voter mobilization techniques work, and they cannot easily be replaced by the Wi-Fi in a coffee shop. If Rubio’s campaign comes to regret these choices, at least they’ll always have Ankeny.

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