The source said Thomas Clayton will be one of the running backs who works out for the Browns. He spent time in Cleveland last season.
Browns coach Pat Shurmur said Monday that Hardesty is wearing a protective boot, but he doesn't know how long the running back will be sidelined. Normal starter Peyton Hillis also is ailing, having missed two games with a hamstring problem.
Chris Ogbonnaya had 11 carries in Sunday's 20-10 loss to the San Francisco 49ers, but he has been with the Browns for just two weeks after being signed off the Houston Texans' practice squad. Brandon Jackson suffered a season-ending toe injury during the preseason.
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The Associated Press contributed to this report.