Until this... yuck:
"While popular opinion might suggest that Johnson was brought to town to back up Clinton Portis, one of Johnson's former coaches has a bold prediction. "He will take over the running back position," said Dick Vermeil, who coached Johnson in Kansas City from 2003 to '05. "That's what I think. He'll push that guy right out of a job." Reported by the Washington Post
The Redskins signed Johnson last week to a three-year contract. Portis, who missed the final eight games last season after suffering a season-ending concussion, returns for his ninth NFL season. He's been the Redskins' starter since joining the team in 2004. Though he's two years older than Portis, Johnson has 755 fewer carries. While the two might begin training camp sharing the workload, Vermeil expects Johnson to open eyes at practice. He says Johnson helped push Priest Holmes, the Chiefs' incumbent running back in Kansas City seven years ago, and Vermeil says he'll push Portis now -- until he surpasses him."