He’s bought fewer TV ads than any candidate for governor. Can his ground game carry him to the Democratic nomination?

If Andrew Gillum is going to win the Democratic primary for governor, he'll have to prove most polls wrong.

A few national progressive organizations that are backing Gillum's run for the state's highest office have activated door knocking and canvassing efforts to try to ensure he does just that.

This week alone in Tampa Bay, both Indivisible, which launched after the 2016 presidential election, and NextGen America, the group founded by billionaire environmentalist Tom Steyer, are engaging in a slew of activities aimed at getting Gillum the Democratic nomination.

Ezra Levin, a co-founder of Indivisible, is joining volunteers in Temple Terrace this weekend to canvass with volunteers on behalf of Gillum. And volunteers with NextGen America are embarking on a door knocking campaign of their own in Tampa Bay this weekend.

"We are committed to throwing the weight of our movement behind Mayor Gillum," Indivisible Project co-executive director Leah Greenberg said in a release this week.

According to that release, Indivisible has already spent thousands on voter outreach and digital advertising, reaching tens of thousands of voters.

Earlier this week, a coalition of eight progressive groups, including The Collective PAC, Our Revolution and People for the American Way announced they were pooling $3.5 million in organizing resources in a coordinated effort to get Gillum elected.

Read more about the groups backing Gillum here and here. 

Whether that work can carry Gillum to victory remains to be seen. Although one internal poll this week showed Gillum had shot to the top of the field the week after his campaign rallies with Sen. Bernie Sanders, most surveys have shown Gillum in the middle of the pack in the competitive Democratic gubernatorial primary.

Politicians behind in the polls often tout a campaign's "ground game" — its ability to bring voters to the polls without reaching them on television. Although Gillum has an energetic following among the most liberal reaches of Florida Democrats, it's unclear he'll be able to turn that energy into a primary win.

Television advertising has always been paramount in Florida, a state with large, diffuse media markets. But Gillum's lack of personal wealth — and the FBI investigation hanging over his city government — have made it difficult for the Tallahassee mayor to fundraise.

Can national organizations knocking on enough doors make up for the fundraising difference in a race with Gillum and four millionaires? Gillum better hope so.