While set to debut the new BMW M8 GTE next year, the German manufacturer is yet to finalize its factory partner for the IMSA portion of its program, which has been run by Rahal Letterman Lanigan Racing since 2009.
Andretti Autosport, which will represent BMW in its upcoming entry into Formula E, is reportedly among the other teams that could be in contention for the GT Le Mans contract next year.
"After the summer holidays we should definitely have our ducks in a row," Marquardt told Sportscar365. "Late summer should be the target.
"Within in the month of September, we should definitely know what we do."
Marquardt explained the process for 2018 is no different than in previous contract-expiring years when the program goes up for tender.
He said they've been pleased with their long-term partnership with the Bobby Rahal-led team, which has delivered numerous wins and championships, including recent back-to-back class victories for Bill Auberlen and Alexander Sims with the BMW M6 GTLM.
"As we are corporate, you obviously have to go through a variety of options and see the strengths and weaknesses," Marquardt said. "We have a very successful relationship with Bobby and his team, and we just go about it as we always do."
Whichever team is selected, Marquardt indicated they would unlikely be part of the manufacturer's program in the 24 Hours of Le Mans, with only its two full-season WEC entries, run by BMW Team M-TEK, currently planned for the French endurance classic.
On the drivers front, Marquardt said they expect to fill the additional seats needed for the WEC program with its existing crop of factory drivers.
"We're really lucky with what we have available to us," he said. "We have a very strong GT and sports car driver lineup and we don't have to worry about that.
"Because of the variety of programs with Formula E next year, we have a plan in mind, and I think it is going well."
He said they haven't ruled out drivers such as Antonio Felix da Costa competing in multiple series next year, particularly with Formula E and WEC set to not feature any clashes.
"We have to see to avoid clashes in calendars but I think at the end of the day, Antonio has shown that he can manage both," Marquardt said.
"He was super quick on the Nordschleife and he's been super quick in every car that you put him in. He still is one of the quickest guys in Formula E."
It's believed at least three of BMW's current four full-season WeatherTech Championship drivers will remain Stateside next year. John Dagys/Sportscar365.com