A "Yes" vote for independence would be an economic mistake for Scotland and a geopolitical disaster for the west, senior U.S. figures – including Alan Greenspan – tell the Financial Times as Washington wakes up to the chance that its closest ally could break up this week.
Having assumed for months that "No" would win comfortably,Washington has reacted with alarm to opinion polls showing that Thursday's referendum is going down to the wire. "We have an interest in seeing the U.K. remain strong, robust and united," said Josh Earnest, the White House spokesman.
Mr Greenspan, former chairman of the U.S. Federal Reserve, said the economic consequences of independence would be "surprisingly negative for Scotland, more so than the Nationalist party is in any way communicating".
"Their [nationalist] forecasts are so implausible they really should be dismissed out of hand," said the normally circumspect Mr Greenspan, noting the pace of decline in North Sea oil production.
Despite Nationalist claims to the contrary, he said there was no chance of London agreeing to a currency union. Differing fiscal policies would also cause any Scottish attempt at using the pound regardless to "break apart very quickly".
"There's no conceivable, credible way the Bank of England is going to sit there as a lender of last resort to a new Scotland," said Mr Greenspan.
Many U.S. officials combine ancestral roots in Scotland and knowledge of the Scottish Enlightenment's influence on the U.S. constitution with strong emotional ties to the UK, an ally the U.S. has fought alongside for 100 years.
"Like many Americans, and given that my name is Robert Bruce, I have an admiration for the Scots, their heritage, and their role in U.S. and world history," said Robert Zoellick, the former deputy secretary of state and World Bank president.