WASHINGTON — (CNN) One of the lead architects in Britain’s decision to leave the European Union said Tuesday the country should officially announce its departure from the post-war bloc “in the next few weeks,” while Prime Minister David Cameron and EU leaders remain at loggerheads over how to proceed with the separation.

“I think we do need to send a message that we’re serious about this,” Nigel Farage, leader of the far-right UKIP party, told CNN in Brussels.

“Let’s crack on,” he said.

Britain voted last week to leave the European Union in a referendum that prompted Cameron to resign and caused a leadership coup in the opposition Labour Party.