"I propose that the Member States discontinue the consideration of a draft legislative act where a number of national parliaments object to it on the grounds of subsidiarity, unless the concerns raised can be accommodated," Tusk wrote.
The European Sherpas and Permanent Representatives are set to meet on Friday for first discussions of the proposal, with a view to have an agreement by the February 18-19 European Council, the letter states.
British Prime Minister David Cameron assessed the draft renegotiation document as showing "real progress" in the four areas he proposed in December, but said via Twitter "more work" needed to be done.
Cameron wants Brussels to allow Britain stay out of the EU movement toward an "ever closer union," to make an explicit statement that euro is not the official currency of the union, to allow national parliaments to block EU legislation and to give Britain independence in its migration policy.
He pledged to hold a so-called Brexit referendum by late 2017 should the proposed reforms fail to take effect.