The champion jockey may be required to ride L’Ami, owned by McManus and trained by Francois Doumen in France, in the Betfair Chase at Haydock.
But Lewis, who is bidding for a seventh victory in nine years in the Grade Two contest at Huntingdon, is hoping McCoy will be released to ride the 10-year-old.
“We hope to have the services of Tony McCoy. JP has always been very good to me as regards Tony in big races,” said Lewis.
Edredon Bleu won the race for four consecutive seasons between 1998 and 2001, Best Mate won the 2002 renewal and Impek claimed the spoils 12 months ago.
“We are going for our seventh win in nine seasons,” said Lewis. “Huntingdon has been a happy hunting ground for us.
“Impek is in fine form. He won well at Exeter (William Hill Gold Cup) and, fingers crossed, we’re hopeful of a very good show at Huntingdon.
“Impek was in the grip of the handicapper for a couple of seasons, and Timmy Murphy deserves a lot of credit for carrying out the decision to change riding tactics at Aintree a year ago.
“He used to be ridden in the middle of the field. He’s not a front runner, but he’s ridden more prominently now.”