Lambert would love the 25-year-old to pen a new deal in the Midlands but at this stage all talks are deadlocked.
"The contract might happen if your club is flying and doing well," said Lambert whose side are just three points above the relegation zone.
"Both (Delph and Ron Vlaar) have got the option to go.
"We're still talking to Fabian and hopefully we can get something done. It would be great for us if we could do it.
"Whether you get the two of them or one (to sign) I don't know."
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