David Cameron, Ed Miliband and Nick Clegg will abandon prime minister's questions tomorrow in order to campaign to save the union.
The unprecedented and dramatic announcement on Tuesday morning by the leaders of the three main Westminster parties came amid fears in London that the momentum was with Alex Salmond and the Yes campaign.
In a joint statement, the three men said: “There is a lot that divides us - but there’s one thing on which we agree passionately: the United Kingdom is better together. That’s why all of us are agreed the right place for us to be tomorrow is in Scotland, not at prime minister’s Questions in Westminster."
They added: “We want to be listening and talking to voters about the huge choice they face. Our message to the Scottish people will be simple: ‘We want you to stay.’"
Prime minister's questions will go ahead, however the duties will fall to the deputies - William Hague and Harriet Harman.
Angus Robertson, the SNP's leader in the Commons, said the No campaign was "in meltdown". He told the BBC it was "panic stations in Westminster".
Salmond said the the No campaign was in "complete and utter disarray". The Scottish first minister added that "they are making this farce up as they go along".
"Together, David Cameron, Ed Miliband and Nick Clegg are the most distrusted Westminster politicians ever - and their collective presence in Scotland will be another massive boost for the Yes campaign," he said.
Appearing before MPs on the constitution committee on Tuesday afternoon, Clegg insisted the trip to Scotland was not last minute. The Lib Dem leader said it would be a "dereliction of duty" on the part of him, Cameron and Miliband not to play a role in the campaign.
A swing for independence has the rival Yes and No campaigns neck and neck ahead of next week's Scottish referendum, the latest poll has suggested. Among those who said they were certain to vote on September 18, support for independence and staying in the United Kingdom was tied on 41%, according to new research from TNS.
There could be some 600,000 voters who have still to make up their minds, with 18% saying they are certain to vote in the referendum but are still unsure how they will cast their ballot.
Yesterday Gordon Brown made a return to frontline politics to campaign for a No vote. The former prime minister encouraged his fellow Scots to reject independence in favour of the transfer of more powers from London to Edinburgh.
With just nine days to go until the referendum vote, Brown's intervention was welcomed by senior politicians, including his traditional Conservative Party rivals.
Northern Ireland minister Andrew Murrison told The Huffington Post the former Labour leader "appears to have found his voice" in the last couple of days. "It sounds authentic. No one can accuse Gordon Brown of being an unpatriotic Scot or Briton, I'm pleased he has belatedly got involved in the campaign," he said.