Professional soccer stadium renderings first began floating around St. Paul City Hall nearly two years ago, well before discussions with Minnesota United FC owner Bill McGuire reignited in May.

And the sides are discussing a St. Paul soccer stadium with more intensity than the mayor’s administration has recently let on.

Mayor Chris Coleman met with McGuire last week for the third time in as many months as St. Paul tries to lure Major League Soccer into a stadium that would be built on the vacant, 10-acre “bus barn” site off Snelling and University avenues.

Coleman’s pitch: anchoring a pedestrian-friendly urban center with an open-air soccer stadium seating at least 18,000 near the light-rail line that connects downtown St.

Minnesota United FC’s "Dark Clouds" fans celebrates forward Christian Ramirez’s goal against Jacksonville Armada FC in the second

Paul with Minneapolis. United FC, awarded an MLS expansion franchise in March, would start playing there as early as 2017.

On the table: the property tax break that Minneapolis has been unwilling to offer United FC, a deal-breaker for a team that would finance the $120 million stadium, the $100 million MLS expansion fee and the $30 million parcel of land near Target Field in downtown Minneapolis.

Coleman’s gung-ho email to key planning staff in April perhaps sums up the mayor’s enthusiasm best — “Hell yeah” — and city officials reviewed potential stadium legislation with outside attorneys on May 15.

State lawmakers, including Gov. Mark Dayton, expressed little interest in helping United financially, but Coleman told reporters on July 9 that St.

Paul could exempt the bus barn site from property taxes because it’s not currently on the tax rolls, anyway.

“The mayor made this really clear,” Tonya Tennessen, a spokeswoman for Coleman’s office, said Monday. “He said he is open to the bus barn site remaining tax exempt, potentially, saying the city has not realized any tax revenues for more than 50 years. Any additional public financing assistance is yet to be determined.

“But it is too preliminary to say what any deal points would be.”

Minneapolis Mayor Betsy Hodges, a key ally of the Coleman administration since before she was elected mayor in November 2013, has shown limited interest in the project.

With little help likely from Minneapolis, which since 2007 has kicked in money for Twins and Vikings stadiums, St. Paul seems United FC’s best option. And United FC seems St. Paul’s best option for remaking a somewhat moribund part of the city.

“We have plans already about how to optimize that site, investments the city would make — the sewers and the green space and investing in the street grid,” Tennessen said. “Those kinds of conversations were happening outside of the soccer stadium (but) a potential soccer stadium could be the catalyst that would allow us to realize our vision for that site.”

This isn’t St. Paul’s first go-round with United FC and McGuire, the former UnitedHealth Group CEO who bought a troubled, second-tier pro soccer team in 2012 and has it within sight of joining the top U.S. professional league.

United beat bids from Minnesota Vikings owners Zygi and Mark Wilf as well as groups from Sacramento and Las Vegas for the expansion team. The impasse on the Minneapolis site is the impetus for current talks with St. Paul, but it’s not the first time McGuire has crossed the river.

Nearly 200 pages of internal emails reveal that Coleman’s administration has been talking to McGuire about situating a professional soccer stadium at the bus barn site since at least the summer of 2013.

In fact, it appears McGuire — a lung doctor and philanthropist — was trading notes with St. Paul city planners and higher-ups in Coleman’s administration long before he formally approached the Minneapolis City Council with his vision for a stadium near Target Field in the city’s West Loop.

That, of course, was also before McGuire and new ownership partners had an MLS expansion franchise. The North American Soccer League franchise formerly known as the Thunder and as the Stars had played in many places, including Central High’s Griffin Field, before finding a home at National Sports Center in Blaine.

The emails are unlikely to eliminate widespread concern that team owners — which include the Pohlad family, owners of the Twins, and the Timberwolves’ Glen Taylor — may not be serious about St. Paul, but they do show McGuire closely engaged with the city and with Rick Birdoff, a principal with Midway Shopping Center owner RK Midway, as early as August 2013.

McGuire’s early concept plans in 2013 predicted a stadium with 24,000 seats.

In May, McGuire again shared his renderings with Coleman after a face-to-face meeting: “Thanks for chatting today. Here are the rough concepts we created a year and a half ago. Bill.”

On May 15, attorneys with the St. Paul-based law firm Messerli and Kramer shared with city lobbyists a draft of legislation that would exempt a professional soccer stadium from property taxes and taxes on construction materials, among other benefits. The legislation does not specify a site or even a city.

Tennessen said Monday that St. Paul did not hire the firm to craft the draft language and declined to say whether it was commissioned by McGuire.

The draft language specifies that team owners spend at least $100 million on construction, not including land purchase, create 1,600 construction jobs and maintain a minimum capacity of 18,000 seats.

Tennessen discredited a report that the mayor has given the team a 30-day deadline to commit to the site.

On April 15, St. Paul Planning Director Jonathan Sage-Martinson emailed Coleman and Deputy Mayor Kristin Beckmann to indicate he had “several people approach me about the possibility of a new soccer stadium being located in St. Paul. … I understand that you Mayor met with the owners a year or more ago and sent a pretty clear message. Let me know if anything has changed from your perspective.”

Coleman’s response later that day acknowledged that discussions with McGuire had previously fizzled, but that the mayor himself remained gung-ho.

“The message I have (for) them was ‘hell yeah,’ he wrote. “They don’t seem interested in us — just not that into us. Thought we could integrate them into the new Midway/bus barn site.”

Since then, Coleman and Beckmann have met with McGuire three times. Louis Jambois, president of the St. Paul Port Authority, attended the first meeting in May.

Andy Greder contributed to this report.

Frederick Melo can be reached at 651-228-2172. Follow him at twitter.com/FrederickMelo.