Theresa May arrives in Brussels for crunch talks insisting the UK will not be "trapped" in Brexit backstop arrangements.
The Prime Minister was greeted by European Commission president Jean-Claude Juncker as she arrived at the Berlaymont after seeing protesters holding signs saying "Don't Crash Out".
Mrs May is meeting EU leaders in the wake of the latest war of words between the two sides.
The spat was triggered by European Council president Donald Tusk saying there was a "special place in hell" for those who pushed for Brexit without a plan.
The PM is expected to stress that changes to the Withdrawal Agreement will be needed to ensure legally binding guarantees regarding the backstop.
At present the backstop, which is intended to prevent the return of a hard border in Ireland, would see the UK continue to obey EU customs rules after a transition period if no wider trade deal had been reached.
Mrs May insists she has a clear mandate from Parliament to seek fresh, binding guarantees on the issue from Brussels.
The PM will hold talks with European Commission president Jean-Claude Juncker, European Council president Donald Tusk and other senior EU figures during her trip to Brussels.
Mrs May is also set to meet European Parliament Brexit coordinator Guy Verhofstadt who joined in with Mr Tusk’s Brexit "hell" analogy.
Mr Verhofstadt tweeted that Lucifer would not welcome such Brexiteers because "after what they did to Britain they would even manage to divide Hell".
Downing Street said Mrs May is "open to different ways" of achieving her objectives on the backstop.
The PM will use the meetings to state Parliament has sent "an unequivocal message that change is required".
One of the PM’s key messages for EU leaders will be the Commons has now made it clear it could support the Withdrawal Agreement as long as concerns about the backstop are addressed.
Mrs May also intends to stress that Labour leader Jeremy Corbyn also has concerns about the backstop, so it is not just an issue for the Tories and their DUP allies.
In Mr Corbyn’s letter to the PM, which follows their Brexit meeting last week, he insists that Labour’s Brexit demands must be enshrined in the Political Declaration setting out future relations with the EU.
Mr Corbyn said securing in law the demands is the only way of achieving Labour support and uniting the country.
He calls for a “permanent and comprehensive UK-wide customs union” that gives the UK a say over future trade deals, and close alignment with the single market, underpinned by “shared institutions”.
The PM will state both sides must "show determination" to get an exit deal "over the line".
Downing Street said the EU meetings are part of a process leading to the Government bringing back a "meaningful vote" on Brexit to the Commons as soon as possible.