Warzycha told the Daily Express: "Our offer is concrete. Zurawski is very interested in joining us because he wants to play in Euro 2008."
Zurawski's lack of first-team action with Celtic could threaten his chances of representing his country this summer, and a move to the United States could help his prospects, even though the MLS is currently out of season.
Warzycha said: "His agent Mark Donaghy is now negotiating with Celtic over the transfer fee. We believe it will be between 200,000 and 300,000 euros (£150,000-£225,000)."