Kevin Payne, D.C. United’s hands-on executive since Major League Soccer’s most decorated club was launched in 1996, has stepped down as club president and will join another team in the league, multiple sources told the Insider. [UPDATE: United has issued a formal statement announcing his departure.]

Payne, 59, was instrumental in the organization gaining a foothold in the Washington sports market and supervised the team’s dominance in the league’s early days.

For years, United’s primary investors were uninvolved and deferred to Payne to run the club and speak of their behalf. He was, in essence, the team’s unofficial owner and, for 10 years, led an unsuccessful effort to build a new stadium in the metro area.

But a new investment group has taken a more active and visible role since the summer acquisition of the team’s operating rights and will now spearhead talks with the city and developers on a stadium project at Buzzard Point in Southwest D.C.

Payne, who was scheduled to address United employees this morning, will join another team in the coming days. The identity of his new employer was not immediately known. [UPDATE at 11 a.m.: He is going to Toronto FC.] He didn’t return a phone message seeking comment this morning.

Jason Levien, United’s general partner and the point man in the club’s new investment group, did not return phone and e-mail messages. Spokesman Doug Hicks said he could not comment.

News of Payne’s departure comes nine days after United was eliminated from the Eastern Conference finals, the club’s first playoff appearance in five years. Despite the team’s resurgence, investors concluded the business side “needs a lot of work,” a source said. The search for Payne’s replacement is underway, said the same person, who wasn’t authorized to speak publicly.

The new president is likely to focus on business operations, granting greater autonomy to General Manager Dave Kasper and Coach Ben Olsen to handle roster decisions.

Despite the organization’s history of success, Payne’s management style wasn’t always well-received. He was a regular visitor to the locker room, attended practices on occasion and consulted with the technical staff about personnel issues. Some saw it as his way of expressing passion for a club he helped forge; others saw it as meddling.

Payne was unquestionably the club’s biggest supporter. When controversial decisions went against United, he didn’t shy from speaking out and taking his cause to league headquarters. His comments to reporters were sometimes too critical and colorful for league standards, resulting in multiple fines. Payne’s hard-charging ethos took a toll: In 2008, he underwent quadruple bypass surgery.

“Nobody loves D.C. United like Kevin Payne,” a source said. “I’m sure he is looking forward to the new opportunity, but this will hurt.”

Aside from serving as president, Payne was also United’s first general manager. He hired Bruce Arena, a successful coach at the University of Virginia, to guide the nascent squad.

United advanced to MLS Cup each of the first four years, raising three trophies, and won the 1998 CONCACAF Champions Cup as the best club in North and Central America and the Caribbean. Under Payne’s supervision, United also won the U.S. Open Cup twice and the Supporters’ Shield (most points in the regular season) four times.

United was the model organization in MLS for many years.

Payne served as United’s president and GM until 2001, when he was named managing director for AEG Sports, which, at the time, operated several MLS teams, including United. Despite the broader role, he kept the same office. Payne returned to full-time duty with United in 2004, the last time the club won the league title.

While United set the standard on the field and in the front office, the club suffered repeated setbacks in stadium efforts. United and the New England Revolution are the last of MLS’s 19 teams without specific plans for a new or renovated venue. Without enhanced revenue streams, United has been losing money since the inaugural season.

Attendance at RFK Stadium this year fell to its lowest average in club history (13,846), a 34 percent decline since 2007 and the third-worst figure in MLS in 2012.

The outlook for a new stadium has improved since Erick Thohir invested in the club in July. He and Levien partnered with San Francisco-based executive Will Chang, who has held a stake in United since 2007. The son of an Indonesian billionaire, Thohir brings a portfolio needed to finance the project.

Levien is a former Democratic Party strategist and sports agent who last month was named chief executive of the NBA’s Memphis Grizzlies. He is in the process of moving to Washington from New York, a sign of deeper involvement with United. However, Payne’s replacement, not Levien, will run the front office on a daily basis, a source said.

Levien’s top priority is navigating the political waters toward reaching a stadium deal.

Despite Levien’s arrival, Payne has remained active in the stadium plan. Just last week he provided updates on negotiations concerning both the stadium and United’s largest sponsorship deal, Volkswagen, which expires this month. He also spoke in detail about the club’s roster philosophy heading into next season.

United is “transitioning toward a new stadium, there’s a new energy, a lot of things are happening,” a person familiar with the situation said on condition of anonymity. “It was just the right time” for a change.