Politicians, religious leaders and trade unionists have called on "everybody of goodwill" to join the "growing opposition" to Donald Trump by taking part in demonstrations against the president-elect.
More than 50 leading public figures have signed a statement urging people to "Stand up to Trump" and protest against his "divisive politics of despair".
The statement describes the election of Mr Trump as "deeply disturbing and a stark warning to us all".
It decries the "significant" growth in racism and claims that the tycoon's election is "encouraging and legitimising a backlash against women's and LGBT+ rights" while creating a "possibly devastating impact on climate change".
"We cannot allow racism to seep deeper into society and whatever our other differences, we must unite together to meet this serious threat," it states.
"We the undersigned therefore urgently call for anti-racists, trade unionists, community and campaign activists, and above all everybody of goodwill, to join the growing opposition to Trump and what he stands for."
Shadow cabinet members including Emily Thornberry, Clive Lewis and Diane Abbott, as well as trade union leaders including the National Union of Teachers' Kevin Courtney and Unite's Len McCluskey, gave their backing to the calls.
Rabbi Lee Wax and members of the Muslim Council of Britain have also supported the statement.
Shadow home secretary Ms Abbott said: "There is a link between inflammatory statements by politicians and racist attacks and hate crimes on the street.
"There has been a rise in such crimes in Britain following the EU referendum and a similar pattern has emerged in the US.
"Now is the time for people of goodwill to unite and stand up to racism."
Weyman Bennett from Stand Up To Racism, which has initiated the demonstrations, said: "Trump's campaign for president was marked by constant scapegoating of migrants, with a key slogan 'build a wall' to keep out Mexican workers and attacks on America's Muslim community.
"We cannot allow these ideas to become acceptable."
Protesters will gather outside the US Embassy in London at the same time as Mr Trump's inauguration on Friday at 5pm.
"Stand up to Trump, Stand up to Racism, No to Islamophobia and Antisemitism, Refugees are welcome, Black Lives Matter" demonstrations are also planned in the capital and Glasgow on March 18.