With a week to go before the Iowa caucuses, presidential candidate Bernie Sanders is pulling out all the Snaps.

The Democratic upstart—who is in a tight battle with Hillary Clinton in several of the early primaries, according to several recent polls—on Sunday kicked off a nine-day Snapchat ad campaign specifically targeted at voters in Iowa.

On Jan. 24, Mr. Sanders’ campaign began running the first of nine planned Snapchat geofilter ads. These ads are visual images people can add to their Snapchat videos only when they are present in specific locations.

In this case, during the final countdown to the Feb. 1 Iowa caucuses, the Sanders campaign is running a new geofilter ad on Snapchat everyday. On Monday, the geofilter ads read “Feel The Bern: One Week Until Caucus Night!”, while Wednesday’s ad reads “Feel The Bern in 5 Days!”

People who are in Iowa can impose one of the signature phrases over a video and share it on the social platform. The hope is that Snapchat users will help spread the message to a wider social audience.

A Snapchat ad for presidential candidate Bernie Sanders Photo: Snapchat

For example, a person in Iowa might shoot a video for Snapchat from one of Mr. Sanders’ appearances and add the “Feel The Bern” geofilter at the bottom of the video. Or an Iowa resident may just make their own personal video and show their support for Mr. Sanders by including one of the geofilters.

Retailers have been known to embrace these sponsored geofilters to help drive their branding and awareness among consumers. For example, Dunkin’ Donuts has urged people to make videos featuring the brand’s imagery when they are visiting specific stores.

Beside Mr. Sanders’ countdown, Snapchat is planning to produce two different Iowa caucus-themed Live Stories. A Snapchat Live Story is a compilation of videos produced by its users that is published for all to watch for a single day. These particular videos will be posted on the day before and day of the Iowa caucus, said a person familiar with the matter. As of now, no presidential candidate has elected to sponsor these videos.

Mr. Sanders is the first Democratic candidate to advertise on Snapchat, and this will be the first time Snapchat has run a geofilter campaign for this many days in a row. On the Republican side, Ted Cruz, John Kasich, Rand Paul and former candidate Scott Walker have all used Snapchat ads.

“We’re leveraging Snapchat to help us turn out young caucusgoers in Iowa who know Sen. Sanders is the best candidate to make college affordable, fight climate change and take on a corrupt political system,” said Kenneth Pennington, Mr. Sanders’ digital director, in an emailed statement.

Clearly, presidential candidates see Snapchat’s as a key place to advertise and maintain an organic presence, given its huge youthful audience. The messaging app, which lets people send short video messages to each other that disappear, claims to have 100 million unique people using it each day.

A Snapchat ad for Bernie Sanders Photo: Snapchat

Whether or not they plan to advertise on the app, most of the candidates, including Jeb Bush, are on Snapchat. But interestingly, among the 2016 contenders, Donald Trump, Rick Santorum and Mike Huckabee don't currently have Snapchat accounts.

Mrs. Clinton does have a Snapchat account, but has yet to purchase any Snapchat ads. While Mr. Sanders has focused on his online and mobile ad campaign (he has over 2.5 million Facebook followers vs. 2.2 million for Mrs. Clinton), Mrs. Clinton’s campaign has been advertising on TV in Iowa and New Hampshire since August and has been a frequent advertiser on TV in Iowa in recent days.

To be sure, Mr. Sanders is also spending some of his ad budget on TV as well.

Write to Mike Shields at mike.shields@wsj.com