The Queen should not have to face the embarrassment of hosting "racist" US president Donald Trump on a state visit, Liberal Democrat leader Sir Vince Cable has said.
Sir Vince questioned why highly controversial international figures are given the honour of royal "panoply" during official trips to the UK.
He told BBC Breakfast: "I honestly don't know why the Government, past governments, embarrass the Queen, embarrass the country, by inviting people here for these ceremonial events, which are completely inappropriate.
"And, I think, what will happen if Trump comes, there will be a major expression of public disquiet that we are honouring somebody who is ... racist, misogynist, indulging the most appalling prejudices."
Sir Vince said Prime Minister Theresa May was regretting her hasty invite to Mr Trump to make a state visit to Britain.
"I think we need to make a distinction between engaging in business-like negotiations with other countries, and, obviously, the United States is the major power in the world, and a key part of Nato, we need to have proper discussions with them, and with him.
"But there is a difference between that and honouring somebody with a state visit involving the Queen, all the panoply of a state visit. It's completely inappropriate.
"I think, frankly, the Prime Minister is embarrassed about having made this offer, probably now finds it rather difficult to retract it."
Sir Vince's comments came as his predecessor as Lib Dem leader, Tim Farron, told the party conference in Bournemouth that the Tories are "breaking Britain" in order to get immigration down.
Mr Farron accused Labour of a cowardly connivance with the Government over EU withdrawal.
The ex-leader said: "Britain's exit from the European Union is making my country poorer, less safe and it is damaging the future of our children.
"There is one promise that Brexit will fulfil.
"It will reduce immigration without changing a single law.
"Because if you turn Britain into a poorer, meaner, insular place, no-one in their right mind will choose to come here.
"So, the Tories are breaking Britain to repel the immigrants. And they do it with Labour's shameful connivance. What a disgrace.
"You can be a (Jeremy) Corbyn or a May and change your mind on Europe to suit the weather, too afraid of the people to ever deserve to lead them.
"Leadership requires courage, not cowardice. We stand between two parties led by cowards and leading Britain to disaster.
"And people know it. They vote for one because they're terrified of the other.
"We must give people hope to vote for, not fear to vote against. Britain deserves something better."
Mr Farron accused Foreign Secretary Boris Johnson of lying over Brexit.
He said: "Patriots are never populists. Because patriots tell their country the truth. It is a treacherous act to tell lies to your country, Boris."
Mr Farron said the Lib Dem party was saved from oblivion during his two years as leader.
"The day I took over as leader, one journalist predicted confidently that 'the party that began with Gladstone will now end with Farron'.
"I saw those assumptions that we were dead and buried and I resolved that we were going to survive, grow and win again.
"The Liberal movement of Gladstone, Lloyd George, Shirley Williams, Jo Grimond and Charles Kennedy, the movement I joined as a 16-year-old, was not going to die on my watch.
"And so, two years ago, I set you a challenge and you rose to it: you picked a ward and you won it.
"We had the first local election gains for our party in eight years, grew our membership, took risks and made ourselves matter.
"We saved the Liberal Democrats and I am proud of every single one of you."