If there's a traditional formula for winning the mayor's office in St. Paul, it's this: Court voters in neighborhoods like Highland Park and St. Anthony Park where Election Day turnout is high. Earn name recognition from years on the City Council or in state politics, and tout union endorsements.

Candidates running for mayor this fall, however, say the city has changed and they aren't following the formula of decades past. As they knock on doors, join in parades and hold meet-and-greets, candidates said they've found a St. Paul that is more progressive and diverse than ever, with one of the state's largest immigrant populations and a cadre of interested young voters.

It is the first tightly contested race in 12 years, since Chris Coleman secured the top office. With Coleman opting not to run for another term, the six people vying to replace him are trying to plot the best paths to victory in a political landscape altered by the city's growth, social media and a surge in involvement by progressive advocacy groups.

"That traditional coalition isn't the end-all be-all anymore, because there are folks all over our city that want a role in city government," said candidate Melvin Carter.

Immigrants account for more than 18 percent of the city's population and about 46 percent of St. Paul residents are people of color, census data show.

St. Paul's population has jumped significantly during Coleman's term, topping 300,000 for the first time in four decades, and downtown has seen a growth spurt with new housing and restaurants. But the city has also seen an uptick in poverty. More than 22 percent of residents are at or below the annual income poverty threshold of $22,339 for a family of four.

Candidates are running campaigns intended to reflect the changing city and said they are focusing on all corners of St. Paul. But they remain uncertain about what their efforts will mean come Election Day — and said a lot is riding on who turns out at the polls November 7.

Social media, shoe leather

Candidate Dai Thao, the First Ward council member, set up what he dubbed the "people's podium" in front of a mattress someone dumped along the street in the Summit-University neighborhood.

A small group of supporters stood behind him as he recently gave a speech about the city's organized trash collection plan, which a campaign member recorded on Facebook Live. A couple minutes later, more than 100 people had seen the clip.

Elizabeth Dickinson ran for mayor in 2005, when Coleman first won the office, and said social media use was negligible then. Now she uses it to stay in touch with people.

"But it doesn't build those initial relationships," she said as she walked door-to-door through St. Anthony Park. She estimated she has knocked on thousands of doors and talked to more than 500 people.

Candidate Tom Goldstein said he has also been doing a lot of door-knocking, in part because he doesn't have as much name recognition as other candidates — Carter, Thao and Pat Harris have all been City Council members.

"I can't just sit back and wait until September and deluge people with phone calls and lit pieces," Goldstein said.

Candidates are making the rounds at summer parades and festivals, like Rondo Days, Highland Fest and the White Bear Avenue Parade. At Rondo Days, Carter couldn't make it 10 feet through the crowd without stopping for hugs and handshakes. He grew up in the neighborhood and has a lot of family ties there.

"This is our new mayor!" one woman yelled.

"Only if you get out and vote," he replied.

Both Carter and Thao live in the First Ward, which has had middle-of-road turnout. In elections over the past decade, 13 percent of the city's voters, on average, were from that ward. Meanwhile, the Third Ward, which contains turnout strongholds like Highland Park and Macalester-Groveland, accounted for 22 percent of voters, on average.

Harris, who lives in Highland Park, kicked off his campaign on the other side of town at the Darul-Uloom Islamic Center on the East Side — a historically low-turnout area.

"We've got a message that's a citywide message," Harris said, and his campaign is not targeting any particular neighborhood. He said he has been touring many communities.

Chuck Repke, executive director of the North East Neighborhoods Development Corporation, led Harris around one corner of the East Side last month. At Hmong Village shopping center, where more than 600 people work, Harris strolled through stalls, asking people how business was going and promising to return with his family.

How much has changed?

Some candidates are also pursuing the support of progressive activist groups that have gained traction since Coleman first ran for mayor. They are now endorsing candidates along with the traditional labor and teacher organizations — and could bring more voters to the polls.

The enthusiasm that made Bernie Sanders so popular in the Twin Cities is still alive, said Rod Halvorson, a board member of Our Revolution Greater St. Paul, which is trying to channel that energy into local politics.

"We don't know whether that will have a big impact, but my gut feeling with 17 years of experience in St. Paul says it will have an impact on the turnout and who people vote for," said Halvorson, a longtime DFL activist.

Former Mayor Randy Kelly, who lost to Coleman in 2005, said the business community and police were the two major endorsing groups that helped him get elected.

"There are a lot more advocacy groups and the times are very different, particularly with the tension between police and the community," Kelly said. "Is the city becoming more liberal, more left leaning? Absolutely."

However, Jim Scheibel, who was mayor from 1990 to 1994, said he sees more similarities than differences in St. Paul politics today compared with decades past. Progressive activism is not new in the city, he said, and candidates have always had to build a broad base that reflects all neighborhoods. But a diverse group of supporters is increasingly essential now, he said — as is the backing of older residents.

St. Paul residents 65 years or older were nearly eight times more likely to vote than residents 18 to 34 years old, according to a 2015 Portland State University study of various cities. Many of those key older voters want a mayor concerned with "the basics," like property taxes, Scheibel said.

Scheibel, like many voters, said he is not sure who will distinguish themselves from the throng of candidates.

"Who can organize?" he asked. "And who can put together a varied coalition of all the different groups?"

jessie.vanberkel@startribune.com 612-673-4649