MLS Commissioner Don Garber said Thursday that he would support the relocation of D.C. United if the club isn’t able to improve the terms of its lease at RFK Stadium and make progress toward building a new facility in the city.

During his annual state-of-the-league address, Garber said he is “very concerned” and “continually frustrated” by United’s unsuccessful efforts to work with the city on a new stadium plan.

“We have to aggressively figure a solution out, and that solution needs to be figured out soon,” he said. “I am concerned about where this team will be in 2012.”

United, a charter member of MLS since its launch in 1996, has been exploring projects that would allow it to leave RFK, a 50-year-old venue that is too large for its purposes, lacks modern amenities and, according to club officials, isn’t conducive to operating a business.

In recent years, proposals to build at Poplar Point in Southeast D.C. and in Prince George’s County have faltered. United’s latest interest is Buzzard Point, a waterfront area ripe for development near Nationals Park in Southwest D.C.

United has sought a partnership with the city, with the club covering most of the costs. Last week, however, Mayor Vincent M. Gray wrote on his Twitter account that “we value DC United & hope they stay in DC. But District is in a challenging fiscal environment now & publicly funded stadium not possible.”

The team has also taken a serious look at moving to Baltimore, which has proposed constructing a stadium in the Westport neighborhood, near the city’s baseball and football stadiums. United President Kevin Payne said two weeks ago that the club is very serious about the Baltimore option.

MLS’s marketing department last week directed surveys to soccer fans in the Baltimore area, gauging their level of interest in a team playing there, either through relocation or league expansion. “This is serious,” Payne said at the time. “This isn’t a bluff.”

According to people close to the situation, who requested anonymity because they weren’t authorized to speak publicly, United has had preliminary talks with the University of Maryland about playing at Byrd Stadium until a new stadium is built in the Washington or Baltimore area. The university’s athletic department is facing substantial budget shortfalls and, one person said, would be open to having United as a tenant.

Until a long-term solution is reached, United is seeking more favorable terms in its lease with EventsDC, which operates RFK. Payne claims United has about $1 million more in expenses than the average MLS team and collects about $1.85 million less in revenue.

“If they can’t get a new and improved lease in D.C., and they’ve got to move to another facility in the region, I will be supportive of that, and in fact will help them do that,” Garber said. “If it means they can’t find a solution in Baltimore, then we’ll have to go through a process as we did with San Jose [which relocated to Houston in 2006] to think about potentially moving the team.”

United owner Will Chang, who is based in the San Francisco area, said he didn’t want to comment. Since taking full control of United 2 1 / 2 years ago, Chang has been seeking local partners to bolster the club’s financial situation and stadium outlook.

“I don’t think he’s very happy about what this is costing him,” Payne said of Chang in a recent interview. “When I say things like ‘the current deal at RFK is unsustainable as a business,’ at the end of the business is a person who is writing big checks. There is a point at which he’s not going to write those checks.”

Payne, who has overseen the stadium initiative on Chang’s behalf, referred questions about Garber’s comments to his communications office. Spokesman Doug Hicks said the club had no further comment.

Garber expressed frustration about the lack of progress on the stadium front, saying: “We have started and stopped a half a dozen times over the last number of years, and at this point, it’s very clear to me there is a traffic jam taking place in your city that probably rivals some of the other traffic jams that take place in your city. It’s been frustrating to get a green light on any road whatsoever that will lead us down a path to have a stadium.”

EventsDC declined to comment on United’s lease and the club’s future in the city.