A senior economic adviser to Republican presidential hopeful Mitt Romney has slammed president Barack Obama's policy towards the eurozone crisis.
In an op-ed in Handelsblatt, Germany's leading business newspaper, R Glenn Hubbard, the dean of the Columbia Business School, said Obama's strategy was "unwise" and revealed "ignorance of the causes of the crisis and of a growth trend in the future."
It received a rebuke from White House officials who said airing the criticism in an overseas media outlet broke with political convention and undermined American foreign policy.
In the piece, Hubbard said it was a mistake for the US to encourage Germany to "stand up financially weak governments and banks in the eurozone".
"Unfortunately, the advice of the US government regarding solutions to the crisis is misleading. For Europe and especially for Germany," Hubbard wrote, according to a New York Times translation of the article from the Handelsblatt.
On Friday Obama said it was vital that European leaders acted swiftly to tackle the continent's crisis. The president was implicitly critical of Germany's calls for more austerity measures.
The Democrats have begun using the perceived failure of Europe's cuts to attack Republican-backed austerity measures as part of their 2012 election campaign.
"There's nothing fiscally responsible about waiting to fix your roof until it caves in," Obama said.
Hubbard argues Obama has taken the wrong tack. "Long-term confidence in solid government financing shores up growth and enables the same scope for short-term transitional assistance," he said.
"Mitt Romney, Obama's Republican opponent, understands this very well and advises a gradual fiscal consolidation for the US: structural reform to stimulate growth."
The op-ed drew immediate criticism from Obama officials. "In a foreign news outlet, governor Romney's top economic adviser both discouraged essential steps that need to be taken to promote economic recovery and attempted to undermine America's foreign policy abroad," said Ben LaBolt, press secretary for Obama's re-election campaign.
Obama said Friday that the US had been in "constant" contact with European officials over the crisis, which he said was a serious threat to the US's own fragile economic recovery.
Obama said the US was strong enough to absorb "some of the shocks from across the Atlantic" but added: "If Europe goes into recession, that means we are selling fewer goods, fewer services – and that's going to have some impact."
The president was speaking ahead of the announcement of a bailout of Spain's banks, potentially worth €100bn. Spain is now the fourth European country after Greece, Ireland and Portugal, to have received a bailout.