The England full-back is ready to leave and has attracted interest from multiple suitors including Monaco.
But Eddie Howe wants cover before thinking of letting go of Trippier, who played 25 Premier League games last season.
Newcastle are reluctant to sell him. Trippier has already had a flavour of the continent after spending two-and-a-half seasons with Atletico Madrid before joining Newcastle.
Toon are finalising the £34million signing of Malick Thiaw from AC Milan and he can fill in at right-back, but he is a centre-half by trade.
The Magpies also have Tino Livramento, who switched to the left side in the latter stages of last season, as well as Emil Krafth and Harrison Ashby.