Alexander Street is friendly territory for Sen. Bernie Sanders and at John Gilbreth�s house, even Banjo the dog is for Sanders.

�He�s ready,� Gilbreth joked as he opened the door for a volunteer. �Free dog food!�

The joke about one of the biggest criticisms of Sanders, that his democratic socialist program is too expansive and costly, is only that, Gilbreth said. He recently purchased the home and is fixing it up for his growing family and will vote for Sanders, he said.

�I just see a lot of similarity with the things he�s talking about and the way I aspire to run my business and run my family,� Gilbreth said.

On Saturday afternoon, David O�Brian and Zach Rubin, armed with a campaign app on their smartphones and umbrellas to keep off the rain, knocked on doors to remind voters that Missouri�s presidential primary is Tuesday and the Democratic contest is undecided.

�This is just something I really have faith in,� Rubin said.

Boone County could be fertile ground for Sanders. Former Secretary of State Hillary Clinton received only 37 percent of the vote in 2008. Columbia has been bypassed by candidates so far, but surrogates are making visits. Heidi Cruz, wife of Republican Sen. Ted Cruz of Texas, stopped Friday in Columbia and Chelsea Clinton, daughter of Democratic candidate Hillary Clinton, will host a �Working Mom�s Roundtable� at 8:30 a.m. Monday at UCP Child Development Center.

The stops were part of the campaign�s effort to persuade voters ahead of Tuesday�s primary. Cruz spoke Saturday in the St. Louis area and in Cape Girardeau, Clinton appeared in St. Louis, Republican Donald Trump held a rally in Kansas City and Sanders rallied supporters in Springfield.

On Saturday, actor Justin Bartha visited Sanders� headquarters at 15 S. Tenth St. He was to talk to voters at Flat Branch Pub that night.

As Bartha entered the office carrying boxes of pizza, volunteers armed with cellphone cameras prepared to take selfies with �The Hangover� actor. The office had a photo booth set up with Sanders-themed props, including cardboard cutouts of the senator�s notoriously unkempt white hair and thick-rimmed glasses.

Bartha, who plans to head off to campaign Sunday in St. Louis, said he wants to use his time in Columbia to thank volunteers and support their campaigning.

�I�ve been interested in Bernie for a long time,� he said. �He�s a true progressive. I was excited when I heard he may be running in the last election, so when I heard he was running now, I was excited, but skeptical � realistically skeptical.�

He added that he has been encouraged by widespread support for the candidate.

Turnout will be crucial in determining the primary outcome, which polls show to be close in both parties. Sanders has outspent Clinton for local television time, buying $90,050 worth of ads to $71,611 for Clinton. Democrats use rules that divide delegates proportionally, putting a premium on competing in every state.

Tao Weilundemo, coordinating Sanders callers Saturday, said that when the campaign began he hoped it would push Clinton to be more liberal. After victories that included the major win in Michigan, he said he is starting to think the nomination is in reach.

The local volunteer effort for Sanders began last summer and has enlisted 1,500 people who are helping in large and small ways, said Persephone Dakopolus, volunteer coordinator with Mid-Missourians for Bernie who is a volunteer herself.

Her fianc� does web design and she is a marketing and communications consultant, but helping Sanders has taken priority since June, she said.

Sanders is calling for higher taxes on financial speculations, a national health care system and federally financed college aid that would eliminate student debt. On the window at Columbia headquarters, there is a sign with an offer: �Democratic socialism explained here.�

Upstairs, in the windows of the apartment above the storefront, there�s another message, in block letters: �Bernie Sanders is an Anti-American socialist.�

The headquarters opened March 3, and the sign was in the window above a few hours later, Dakopolus said.

�Free speech, right?� she said. �It�s a beautiful thing.�

Tribune reporter Alicia Stice contributed to this story.