The Rockies have had interest in Redding since before the July 31 Trade Deadline, but nothing came of it because the Nationals were asking for outfielder Dexter Fowler, Colorado's top prospect, in return.
Now, Washington is trying to acquire center fielder Carlos Gonzalez, whom Colorado acquired last month in the Matt Holliday trade.
Gonzalez has been on the Nationals' wish list since 2007. He was signed by the Diamondbacks as a non-drafted free agent on Aug. 3, 2002, and became one of the team's top prospects.
Gonzalez's best season in the Minor Leagues was in 2006, when he led the Arizona farmhands with 99 RBIs and ranked fifth with 23 homers.
A little over a year later, the Diamondbacks traded Gonzalez to the Athletics as part of an eight-player deal on Dec. 14, 2007.
Gonzalez made his Major League debut on May 30, 2008, with Oakland, and hit .242 with four home runs and 26 RBIs.
Lastings Milledge served as the Nationals' center fielder in 2008, but the team considers him a corner outfielder.
The source also said that more players could be involved in the deal, but declined to say who they were.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.