Per ESPN's Chris Haynes, Barton turned down an offer of $42 million over four years from the Nuggets in early October.
Haynes noted Denver's proposal to Barton was the most it could offer under the NBA's salary-cap rules, but his agent, Aaron Goodwin, told him to "bet on himself."
It's a move that could work out well for Barton. The 27-year-old is averaging a career-high 15.3 points and 4.1 assists per game this season. He's been a bargain for the Nuggets, who signed him to a three-year deal worth $10.6 million prior to the 2015-16 season, per Spotrac.
However, Haynes also pointed out there are only seven teams projected to have more than $10 million in cap space this summer in a deep free-agent class for wing players, with names like Kevin Durant, LeBron James, Paul George, Trevor Ariza, J.J. Redick, Avery Bradley and Kentavious Caldwell-Pope all potentially available.
The Nuggets have been a surprise playoff contender in the Western Conference this season. They are 43-35, one game behind the Minnesota Timberwolves and New Orleans Pelicans for the last two playoff spots, with four games left to play.