Liberal Democrat leader Tim Farron is to say he is proud to claim the mantle of "remoaner in chief", as he urges pro-Europeans to "stand up and fight" to keep the closest possible ties with the EU.
At a rally opening the Lib Dems' spring conference in York, Mr Farron will acknowledge that he is taking a "political risk" in speaking out against the direction in which Prime Minister Theresa May has taken Britain since the referendum vote for Brexit last year.
But he will insist that opposing a hard Brexit is "the right thing to do". And he will forecast a future of "numbing shame" for Brexiteers when they have to explain to their children and grandchildren their role in the "senseless lurch into division, hardship and intolerance".
Mr Farron's predecessor as leader, former deputy prime minister Nick Clegg, will attack Brexiteers as "shameless pedlars of fake news and fake hope", dismissing their predictions of a swift trade deal and a boost to Britain's economy from Brexit as "patently false".
Kicking off the three-day conference, Mr Farron will tell delegates he was "incredibly proud" to be named Remoaner of the Year by pro-Brexit campaign group Leave.EU.
"If remoaning means standing up for EU citizens who have made their lives here in the UK... demanding that the British people have the final say in this process... standing up for a family of nations that has healed the wounds of two world wars and a terrifying cold war, then I am proud to be your remoaner in chief," he is expected to say.
Mr Farron will say: "It might be a political risk for us to speak out against the direction our country is going, but it is the right thing to do.
"Because what Britain does in the next two years will define us for the next one hundred.
"So now is not the time to sit down and shut up. Now is the time to stand up and fight."
Two years on from the disastrous 2015 election which saw his party lose its share in the coalition government and reduced to a rump of eight MPs - now increased to nine - Mr Farron will say he is "fed up to the back teeth with defeat" and will urge the party to focus on winning again.
Speaking a day after legislation paving the way for Brexit won royal assent, Mr Farron will urge delegates not to respond with "despair".
"This is the place for you if you have had it up to here with despair, if you are defiant, if you are determined that a bleak future of a closed, intolerant divided Britain is not inevitable," he will say.
"This is the place for you if you believe that there is still a road to a Britain that is open, tolerant and united.
"This is the place for you if you have the stomach for the fight of our lives, for the country we love, for the cause that is right.
"Because if you believe that a better Britain is possible then the Liberal Democrats are your only vehicle for getting there, so don't waste another minute, get on board because the future is as yet unwritten. We intend to write it."