Boris Johnson's Europe advisor, David Frost, will be in Brussels for introductory meetings today and tomorrow
According to the BBC, he is set to pass on the message the UK is firmly leaving on 31 October. It's a similar message to what UK Brexit minister, Stephen Barclay, said overnight as he spoke with EU chief Brexit negotiator, Michel Barnier, yesterday:
The response from EU sources (from different media sources) suggest that the EU position hasn't changed and that Barnier has said that he is ready to meet up with UK negotiators at any time but will only work within the EU's existing mandate.
And that means no renegotiation of the withdrawal agreement and that the backstop cannot be abolished whatsoever.