British and EU negotiators on Tuesday scrambled to put together a draft text for a Brexit deal with just two days to go before a key European summit. Both sides voiced cautious optimism that an accord could be reached this week, though European ministers warned they would not let Britain use Northern Ireland as a back door to the single market. EU chief negotiator Michel Barnier told member states a legal text must be on the table by Wednesday morning at the latest if it is to be signed off by leaders at the EU summit starting Thursday, in time for a special sitting of the British parliament on Saturday.