The eurozone debt crisis has badly shaken faith in the euro, with more than half of Europeans seeing the single currency as bad for their economies, according to an opinion poll published on Wednesday.

"Transatlantic Trends 2012," a major annual survey of public opinion in the United States and Europe, also found that Europeans strongly approve of U.S. President Barack Obama but know little about his Republican challenger in the November election, Mitt Romney.

Fifty-seven percent of people questioned in 12 European Union countries, including both eurozone states and countries outside the single currency area, said the euro had been or would be a bad thing for their country's economy, up four points from a similar poll last year.

The survey, by the German Marshall Fund of the United States, a U.S. think tank that promotes cooperation between North America and Europe, and the Compagnia di San Paolo, an Italy-based private foundation, also tested public opinion in the United States, Russia and Turkey.

About 1,000 people were questioned in each country in June, either by phone or in person.

In Spain, the latest focus of the nearly three-year-old eurozone debt crisis, 57 percent of people thought the euro had been bad for the Spanish economy, up three points from last year.

The poll found an increasingly negative view of the euro in several non-eurozone countries, with 89 percent of Britons, 84 percent of Swedes and 71 percent of Poles saying euro membership would be bad for their economies, all up sharply from last year.

In both Spain and Germany, the eurozone's most powerful economy where there is rising public opposition to bailing out crisis-hit eurozone countries, just over a quarter of people polled wanted their countries to leave the euro altogether.

Despite the economic crisis, 61 percent of Europeans still considered EU membership to be good for their economies, but that was down six points from last year.

European Support for Obama

The survey found 82 percent of Europeans had a favorable opinion of Obama, who is seeking re-election in November.

When asked about his Republican rival Romney, 38 percent of European respondents either said they did not know or refused to answer. Thirty-nine percent had an unfavorable view of Romney while just 23 percent thought well of him.

If Europeans could take part in the U.S. presidential election, an overwhelming majority (75 percent) said they would vote for Obama, while only 8 percent would back Romney.

Approval of Obama's foreign policies in Europe remains high at 71 percent, though that was down 12 points from soon after he took office in 2009, the poll found.

The poll was carried out before Romney's trip to Europe and Israel in July when he angered Palestinian leaders by calling Jerusalem the Israeli capital and annoyed Britons by questioning their readiness to host the Olympics.

The U.S. poll found 57 percent of Americans had a favorable view of Obama and 40 percent unfavorable. Forty-four percent viewed Romney favorably while 49 percent disapproved of him.