“We’ve got to look at the risk of a more populist American public and the U.S. Congress deciding that China is the reason our economy isn’t growing enough,” the American official said.

Image The Dalai Lama's visit to the White House on Thursday angered China on a territorial issue that it considers sacrosanct. Credit... Michael Reynolds/European Pressphoto Agency

Economists say the renminbi is undervalued by 25 to 40 percent, a wider gap than at any other time since 2005, when, under pressure from the Bush administration, China decided to allow the renminbi to float in a narrow band against the dollar and other currencies. The renminbi appreciated 21 percent, but has not moved at all since July 2008. This month, Ma Zhaoxu, a Foreign Ministry spokesman, rejected an unusually public call by Mr. Obama for China to revalue its currency, saying that “the value of the renminbi is getting to a reasonable and balanced level.”

The problem for the Americans is that job creation is also a priority for the Chinese government, because the legitimacy of the Communist Party is based largely on economic growth. A year ago, when the global recession resulted in a severe slump in exports, Chinese officials said 20 million migrant workers lost their jobs. The export industry in China is only now starting to recover, and the low value of the renminbi is crucial for Chinese companies selling goods abroad.

“With economic and trade issues, we’re in for a very difficult year,” said Kenneth G. Lieberthal, a scholar at the Brookings Institution who worked on China policy in the Clinton administration. “I see Chinese protectionism growing on the ground as well as on the U.S. side, with midterm elections coming up.”

But some economists say China is likely to let the renminbi rise by about 5 percent to help stave off inflation, a growing concern among Chinese policy makers. Historically, high inflation has stirred unrest in China.

Economists say the Obama administration and European allies can press China to revalue the renminbi by threatening to impose more tariffs on manufactured goods. Last fall, the American government imposed tariffs on Chinese tires and steel pipes. European officials have privately said that China’s increasingly unyielding stance on issues like human rights has made it politically easy for European governments to toughen up on tariffs.