DETROIT, MI -- A grass roots effort to bring a Major League Soccer team to Detroit could get a huge boost this spring if a longtime backer with local ties finalizes a plan by June 15 to build a stadium downtown and attract investors.

Dan Duggan, Detroit Mayor Mike Duggan's younger brother, said Wednesday he's about "80 percent" confident a USL Professional Division team will play games in downtown Detroit starting March 2015 in a $5 million, 5,000-seat outdoor stadium.

And if that happens, this team - one that's currently nameless - would have a chance of being absorbed by the 19-team Major League Soccer (MLS) within the next five years or so, Duggan said.

"If you look around at the 14 teams that are in USL Pro, they got anywhere from nice parks and high school stadiums to soccer-specific stadiums," said Duggan, who recently signed a preliminary agreement with the USL. "But given that this is the Detroit market, and in my mind one of the ten major markets in the country for soccer, we're not going to do this in a high school stadium.

"We need a soccer-specific stadium."

Duggan declined to reveal any specific locations in downtown Detroit where he'd like to see a stadium built or names of potential investors, but said he's keeping all his options open and willing to talk to anyone interested in backing the effort.

Duggan added that he hasn't sought advice from brother Mike Duggan since he's so tied up with mayoral duties in the Motor City.

Mike Duggan, 55, is 18 months older than Dan; both grew up on Detroit's west side.

"He got things that need to be done that aren't related to what I'm doing," Dan Duggan said of his brother. "Everything that we're going to do is going to be done with private money and people who are in business (in Detroit)."

The USL (United Soccer Leagues) season kicked off on March 22 with its previous two league champions, Orlando City (Fla.) (2013) and the Charleston (S.C.) Battery (2012) squaring off at Charleston's Blackbaud Stadium, the first soccer-specific stadium in the U.S.

Orlando City recently became the fifth USL team that will move to the MLS and serves as a model for Duggan in his effort to convince MLS officials his new USL team will be viable enough to eventually make a move.

"What (MLS officials) really want to see is if you’re going to have fan support, if you’re going to have corporate support, if you’re going to have sponsors and civic people behind you," Duggan said. "MLS is not going to have a failure."

Duggan believes an outdoor, soccer-specific stadium with a grass field can be built in downtown Detroit in 60 days once plans are approved and land is purchased or leased to develop on.

"It won't be hard if I get the deal by June 15," said Duggan, when asked of the chances of building a stadium that's ready for next season. "We can build a stadium in 60 days.

"If I get this done by June 15, that gives us plenty of time to build a stadium; there's a USL Pro team that started up in Sacramento and they're going to build their stadium in 60 days after they just got approval in January."

Duggan owns the Michigan Bucks, a USL Premier Development League team founded in 1995.

The Bucks, composed of mostly local players ages 23 and under, proved in 2012 they can be competitive against the big boys and play MLS-caliber soccer.

The Bucks beat the league's Chicago Fire in a Lamar Hunt U.S. Open Cup game at Pontiac's Ultimate Soccer Arenas.

No matter what happens to Duggan's plans to get a new USL Professional Division team in downtown Detroit, the Bucks will continue to play games in the USL's Premier Development League.

Duggan said he'd like to fiend a new USL Pro team with as many talented local players as he can because he's convinced this area has enough to compete for championships.

"There would be a pro team over the Bucks, eventually there would be a youth academy, and we'd have an MLS partner (in Detroit) and an international partner," Duggan said of his vision. "It's going to have arms that reach into every level of soccer."

Duggan said that he hopes create a contest for soccer fans to create a name and logo for the new Detroit USL Pro team once his stadium and investor plan is accepted by USL officials on or before June 15.

He'd then, under this scenario, hire a general manager, a coach and start putting the team together this summer so it is ready for a 28-game regular season (with about 14 home games) next year.

"We'll have a MLS partner, so we'll play MLS games, too," Duggan said. "We'll have an international partner that comes in July (2015) - a major international team that the world knows that will play one or two exhibition games.

"We'll have US Open Cup games that hopefully we'll host, and we assume we'll qualify for playoffs."

Duggan is open to the idea of having a downtown Detroit stadium that could also be a home to other teams like the Detroit City FC of the National Premier Soccer League, the Bucks or a potential women's pro team.

He also would be willing to host high school games at the venue or use it for other events like concerts or festivals.