The UK's political parties must "put politics aside" and "work together" to secure a positive Brexit deal, Wales' first minister will say later.
Carwyn Jones will claim the negotiations provide an opportunity to offer a "kinder, fairer politics".
Of the nations of Europe, Mr Jones is expected to say: "There is more that unites us than divides us."
He will speak of "a continent wanting, fundamentally, the same things; peace, prosperity and a better tomorrow".
Mr Jones is due to speak on Wednesday at an event at the EU Commission's offices in Cardiff to mark Europe Day - an EU-wide celebration of peace and unity across the continent.
"We are leaving the European Union, but we are not leaving Europe," the first minister is expected to say.
"I believe that the UK can choose this opportunity to re-engineer our relationship with our European partners in a way that safeguards common bonds and, in doing so, help us make real our ambition of a kinder, fairer politics.
"I am, therefore, challenging every political party in Wales and the UK to put politics aside and see Brexit through a wider lens.
"Let us work together in a new spirit of partnership to build a more positive relationship with our European partners over the next twelve months and achieve a settlement which the next generation can be proud of."
'Death bed conversion'
Mr Jones's call for cross-party working follows a heated exchange on Brexit with Plaid Cymru leader Leanne Wood in the Senedd on Tuesday.
Ms Wood criticised the Welsh Government for striking a deal with UK ministers to settle the row over claims of a Brexit "power grab" by Westminster, claiming the agreement "weakened" the assembly's authority.
There was uproar in the chamber when Mr Jones accused the Plaid leader of sounding like Conservative MP Jacob Rees-Mogg - an arch-critic of the UK government's Brexit strategy - in her use of words such as "capitulation", "betrayal" and "dodgy deal".
Leave campaigner and Monmouth Conservative MP David TC Davies said: "It's a bit rich for the first minister [who is stepping down later this year] to have a death bed conversion to 'kinder, fairer' politics.
"At every step since the referendum his actions have been divisive, and his arrogant grandstanding has belied the result of the referendum, and indeed the will of his own constituents - who voted overwhelmingly to leave."