Theresa May is in Brussels to press EU leaders for legally binding changes to the Brexit deal.
The PM will insist the UK will not be “trapped” in the backstop – the plan to avoid the return of Irish border checks whatever UK-EU trade deal is agreed.
She will say the plan must change if it is to win the support of MPs who urged her to seek “alternative arrangements” when rejecting the deal last month.
However, the EU has repeatedly ruled out changing the withdrawal agreement.
Anti-Brexit protester Mark Johnson jumped in front of Mrs May’s car as she arrived. He was bundled out of the way by security staff and was unhurt.
Once inside the European Commission’s headquarters Mrs May was greeted by EC president Jean-Claude Juncker, with the pair shaking hands for the cameras before starting their talks.
Mrs May’s visit comes after the row over Wednesday’s outburst by Donald Tusk, who declared there was a “special place in hell” for those who campaigned for Brexit without a plan to deliver it safely.
MPs who backed Leave in the 2016 referendum reacted with anger to the comments, accusing the European Council president of “arrogance”.