The two men still were together Monday night in Denver. Marshall has been seeking a trade since the spring, and other NFL teams have explored the idea of trading for him.
Marshall didn't practice in Monday evening's drills despite saying Sunday he was healthy.
Two NFL sources told The Denver Post that McGuire sought out Broncos management to figure out where they stood on extending Marshall's contract.
The paper reported the Broncos told McGuire they were not interested in reworking the deal, which has one year and $2.2 million remaining.
He wants a trade and/or a new contract, sources told Schefter. The Broncos are adamant they won't give him either, so it appears to be a standoff.
Adam Schefter is an NFL reporter for ESPN Insider.