But writing in Britain's Sunday Telegraph, Barnier said Brussels remained unconvinced after "intense discussions with EU member states on the need to guarantee the integrity of the EU's Single Market, while keeping that border fully open".
"The backstop is the maximum amount of flexibility that the EU can offer to a non-member state," he stated.
"I am not optimistic about avoiding a 'no deal' scenario but I remain determined to explore all avenues that the UK government will present that are compatible with the withdrawal agreement," Barnier added.