The owners of the wildly popular semi-pro Detroit City FC soccer club want to move their team into a professional league as soon as 2018, but they say they need an infusion of capital first.

That's because they'll need millions of dollars to cover an expansion fee to buy into a pro league, and to cover an expense they've not had since launching the club in 2012: player salaries.

As a semi-pro team in the National Premier Soccer League, a fourth-tier organization in American soccer's organizational pyramid, Detroit City doesn't pay it players. The amateur club, which begins its 2017 exhibition matches this weekend, has an operating budget of more than $1 million this season, DCFC co-owner and COO Todd Kropp said. It played last season to sold-out crowds of 5,255 a game at Hamtramck's Keyworth Stadium, which the club is spending more than $1 million to improve and expand. It will seat around 7,000 this season.

Talks are ongoing to find an investor, or investors, who can provide the team the cash it would need to become a professional soccer club.

"We recognize, if our intent is to take to it to a higher level, we've got to be able to bring in the revenues to support a professional club," Kropp said. Turning pro would mean more home games, which is an increase in both expenses and revenue.

Detroit City also has opened conversations with the two leagues that are one level below Major League Soccer — the premier U.S. pro league that's considering expansion to Detroit. Kropp said DCFC is talking to the New York City-based North American Soccer League and the Tampa, Fla.-based United Soccer League.

The NASL and USL have provisional Division II status this year that was granted by the United States Soccer Federation, the Chicago-based governing body known as U.S. Soccer. There currently is no Division III league, the lowest level of professional soccer, but USL announced plans earlier this year to launch a D-3 league in 2019.

Both NASL and USL still have to meet undisclosed U.S. Soccer criteria to remain D-2 leagues beyond this season, and that uncertainty clouds Detroit City's plan.

"The soccer landscape in the U.S. continues to evolve every day. There are still a lot of details that need to be clarified regarding the D-2 and D-3 leagues so we can't really say right now that there's any particular preference," Kropp said.

Kropp did say Detroit City has "talked extensively" with the North American Soccer League.

The NASL, which began play in 2011, currently has eight teams and players reportedly earn between $15,000 to $100,000 a season. It has deals for games to air on beIN Sports and ESPN3, and clubs have local TV deals a league spokesman said. NASL is averaging nearly 6,000 fans per game, and its split-season format is 16 spring and 16 fall games. Rosters are 30 players.

NASL interim Commissioner Rishi Sehgal said the league will add four teams going into 2018, and intends to eventually be at 18 to 20 clubs. The NASL said its expansion fee is more than $1 million, but less than $10 million, but would not be more specific.

Sehgal said he's attended a Detroit City game, and is impressed by what the owners have created.

"What they're doing is an exciting project. They started the club for the right reasons," he said, adding that Detroit is a market that NASL would like to be in.

The other option for Detroit City is the USL, which also launched in 2011, but has 30 teams and a developmental relationship with MLS, which owns and operates 10 USL clubs.

The USL said its franchise fee is $5 million. Its clubs play 32 matches a season. Last season, they averaged 3,439 fans per game — noticeably lower than Detroit City's average.

USL games air on ESPN3 and ESPNU, and on SiriusXM satellite radio.

An above-average USL player is estimated to earn $2,000 a month, with some making $3,000 and more, according to The Washington Post.

The league is adding a Nashville team in 2018. It said it will announce later this year its expansion plans through 2020.

In the meantime, Kropp and his four co-owners need to find a wealthy benefactor. In the past, the owners have had what Kropp termed a "couple of serious offers" but they were not a proper fit.