Donald Tusk and David Cameron. | Toby Melville - WPA Pool/Getty Images Tusk ready to deliver UK deal, but migration questions remain European Council president says he will send draft agreement to EU leaders on Tuesday.

A draft deal on the U.K.'s demands for renegotiated membership of the EU will be ready by midday Tuesday, but elements of controversial migration reforms must still be agreed upon, according to an EU diplomat involved in the talks.

European Council President Donald Tusk tweeted Monday evening that he would soon publish his proposal "for a new settlement" for the U.K. in the EU.

Talks on the outstanding issues continued late into Monday evening. Differences remained on Britain's insistence on an "emergency brake" temporary ban on in-work benefits for EU migrants for four years, as well as on a guarantee that non-eurozone countries can have some input in eurozone economic policies.

Tomorrow around noon I will table proposal for a new settlement for #UKinEU. Good progress last 24 hours but still outstanding issues — Donald Tusk (@eucopresident) February 1, 2016

According to two EU officials, Tusk has been leaning towards leaving blank the number of years for which an emergency brake would apply.

"Tusk would prefer to keep the number for the negotiations," a diplomat said. "He checked with some Eastern European states on the welfare issue, some of the member states said 'don't put in a figure until it's confirmed'."

British Prime Minister David Cameron's request that the rights of non-eurozone members be protected by a safety mechanism is nearly concluded, the EU sources said. The text will contain details of a basic safety mechanism that would allow non-eurozone countries to request a eurozone issue be referred to the European Council, but they would not have the final decision.

In this way, Tusk is complying with a French demand that the new mechanism doesn't give the U.K. a veto on eurozone decisions.

"Tusk phoned [François] Hollande who made clear what he needed, and Tusk made clear he would take that on board," the EU diplomat said.

Tusk left a Sunday evening meeting with Cameron saying there was "no deal" and setting a 24-hour deadline for an agreement to be reached. Tusk set a deadline of Tuesday for sending the draft agreement to the EU's 27 other leaders to give them enough time to consider the reforms in detail ahead of a February 18 summit.

Downing Street is likely to give a detailed response to Tusk’s statement on Tuesday, according to the Guardian, which will explain any legislative changes that are needed.

Cameron has been pushing for a deal before March so that he can hold the referendum in June 2016. If EU negotiators are not able to settle on a first draft of the agreement within the next few days, the whole process could be delayed.

Besides the controversial demand for a ban on welfare benefits for EU migrants, the U.K. is also encountering resistance from France on a proposal that would give Britain and other non-eurozone countries the ability to call a summit on eurozone economic policies they find troubling.

"To people in France, the euro is important and we need to create growth and stability," a French official said. "If they know an EU country has a way to block our destiny, that’s not right."

European Commission spokesman Margaritis Schinas said that even with the EU institutions' agreement on Cameron's draft, it does not guarantee the support of the other 27 member states.

“Progress has been made at the political and technical level notably following President [Jean-Claude] Juncker’s meeting with Prime Minister Cameron here at the Berlaymont on Friday and President Tusk’s meeting with the prime minister yesterday," he said at a press conference in Brussels Monday. "However we are not there yet."

"It is not enough for the Commission and the Council lawyers to agree," he said. "This is a process that works at 28 and the Commission works for all 28 member states of the Union."