The Redskins, who worked out Orleans Darkwa on Sunday as well, have been hit with several injuries at running back. They lost rookie Derrius Guice to a season-ending torn ACL in the preseason opener. Two backups, Samaje Perine and Byron Marshall, are out with ankle injuries. The team waived another back, Martez Carter, on Saturday with an injury designation.
That left the Redskins with only three healthy backs in practice and a desire to add more, which led them to Peterson. There had been no contact between the sides until Sunday afternoon after the team met with Charles and worked out Darkwa.
Peterson told ESPN's Josina Anderson on Monday that he did a workout session with the Redskins and it's now complete.
Coach Jay Gruden said the team isn't looking for a starter, as that job belongs to Rob Kelley.
"We want to get physicals on them just in case," Gruden said of Peterson, Charles and Darkwa. "We've had very unlucky situations with our running backs. If something else happens, we'll be really, really, really thin. We want to make sure we're covering all our bases right now, and we'll address it when we feel like we have to."
Peterson, 33, made seven Pro Bowls in 10 seasons with the Minnesota Vikings, but the team made him a free agent when it declined to exercise an option in his contract last year. Peterson signed a two-year deal with New Orleans, but he was traded to Arizona on Oct. 10. The Cardinals released him after the season.
Peterson ranks 12th on the NFL's all-time rushing list with 12,276 yards. He has added another 2,015 yards receiving. In 2012, Peterson rushed for 2,097 yards -- second most in a season, after Eric Dickerson.
Last season with Arizona, Peterson had two games in which he rushed for 293 yards, but in four others, he gained a combined 155. He was suspended in 2014 after he was charged with child abuse.
Charles, 31, is a four-time Pro Bowler who has rushed for 7,556 yards and 5.4 yards per carry. He also has caught 308 passes for 2,586 yards and 20 touchdowns. He spent nine years with Kansas City and last season with Denver. Injuries limited him to a combined eight games in 2015-16.
"I have no idea what's going to happen, but he's certainly someone I think a lot of, as both a teammate and a person, and think he's the kind of player who can bring a lot to the table," said quarterback Alex Smith, who played with Charles in Kansas City. "There were a few years where he was the bulk of the offense, run game and pass game. Never came out of the game. He was that kind of player, and he was doing that for several years there."
If Marshall isn't ready to open the season, the Redskins might want another backup to third-down back Chris Thompson. Gruden has said that Thompson might be limited early in the season. They also have Kapri Bibbs, who could serve in that role.
Darkwa spent the past four seasons with the New York Giants, emerging last season with 751 yards rushing, with 154 coming in the season finale win over Washington.