In the aftermath of rookie Derrius Guice's crushing season-ending ACL injury, coach Jay Gruden's initial response was to spurn the veteran free-agent market in favor of the younger tailbacks already on Washington's roster.
This is the first reported visit of the year for Peterson, who was released by the Cardinals in March. Now 33 years old, the seven-time All-Pro selection is fully healthy after his 2017 season was ended prematurely by a neck injury.
Although Peterson averaged just 3.4 yards per carry last year, he broke the 130-yard mark twice in six games as Arizona's one-dimensional bellcow runner. Behind a porous offensive line, he showed impressive burst, power, jump-cuts and breakaway speed.
Teams have been reluctant to sign him as a complementary back in a committee attack, however, because his presence on the field too often telegraphs a running play.
Charles, 31, has been an afterthought in free agency after rushing for 296 yards on 69 carries (4.3 yards per carry) last year. Although the four-time Pro Bowl selection flashed promising playmaking ability in September, his role diminished over the next three months as Denver's season descended into deep disappointment.
Although Peterson and Charles are the headliners here, Darkwa is also working out for the team's brass on Sunday.
The 26-year-old led the Giants with 751 rushing yards last season, averaging a respectable 4.4 yards per carry.
On the positive side, he's fully healthy after undergoing surgery to remove a stabilizing plate from his leg in May. On the down side, Football Outsiders Almanac 2018 tracked him with the lowest rate of broken tackles among starting running backs in 2017.