Japan's opposition party says it would refuse to buy American government bonds denominated in US dollars, if elected.
The chief finance spokesman of the Democratic Party of Japan, Masaharu Nakagawa, told the BBC he was worried about the future value of the dollar.
Japan has been a major buyer of US government bonds, helping the US finance its Federal budget deficits.
But, he added, it would continue to buy bonds only if they were denominated in yen - the so-called samurai bonds.
"If it's [in] yen, it's going to be all right," Mr Nakagawa said in an interview with the BBC World Service.
"We propose that we would buy [the US bonds], but it's yen, not dollar."
BBC NEWS | Business | Japan 'would avoid dollar bonds'