"We are excited to bring James back into the fold for next season," said Donnie Nelson, the team's president of basketball operations. "His tireless work ethic and locker-room presence were a large part of our success last year."
The Mavericks have kept the offer on the table all summer despite the fact that Singleton, as of Monday, represents their 17th guaranteed contract for the 2009-10 season.
NBA teams are limited to carrying 15 players, and, thanks to the recent arrivals of Shawn Marion, Drew Gooden and Tim Thomas to flank Dirk Nowitzki, minutes would appear to be scarce in the Mavericks' frontcourt.
Singleton, though, is a virtual lock to be among the final 15, winning admirers in his first season under coach Rick Carlisle for his energy and production whenever he did get playing time.
Sources told ESPN.com that the Mavericks are actively pursuing two-for-one trades in hopes of easing the roster logjam before training camp starts Sept. 28, with center Nathan Jawai and swingman Shawne Williams among those being made available.
But completing such deals, especially this close to camp, is difficult, with many teams having largely completed their offseason business and several teams around the league planning to carry only 13 or 14 players in the midst of a depressed economy.
Even without another trade, Dallas' roster number will to drop to 16 through the release of veteran swingman Greg Buckner, who was acquired from Memphis in the four-team deal that netted Marion in July.
Buckner became eligible to be traded again last week, but Mavericks owner Mark Cuban has said publicly that Buckner will be let go to try to find another job before camp -- instead of launching his third stint with Dallas.
"Given our depth at that position, coupled with the number of guaranteed contracts, there is simply no room on our roster," Nelson said.
Singleton averaged 5.1 points and 4.0 rebounds in 62 games with the Mavericks last season. The qualifying offer from the Mavericks is worth $175,000 more than the league minimum for a player with three seasons of service time ($855,189), so staying with Dallas was always the most likely outcome for the 6-foot-8 forward when it became apparent he would not be able to land a two-year deal elsewhere.
Marc Stein is a senior NBA writer for ESPN.com.