American frustration with Beijing's trade policy boiled over today into a congressional vote that was expected to back a threat of punitive tariffs on Chinese imports to compensate for perceived manipulation of the level of the yuan.

Exporters and politicians in the US have become increasingly frustrated with the Chinese government's interventionist tendency to keep its currency artificially weak – a practice that means exports of Chinese goods are cheap around the world, while imports of foreign goods are expensive to Chinese consumers.

In a rare display of cross-party consensus, the US House of Representatives scheduled a swift vote on a bill to authorise the US commerce department to impose duties on Chinese imports to cancel out what some politicians claim is a 40% discount on their price on global markets. America's trade deficit with China is expected to hit $250bn (£158bn) this year.

"It's time to deliver a strong message to Beijing on behalf of American manufacturing: Congress will do whatever it takes to protect American jobs," said Tim Murphy, a Democratic congressman sponsoring the bill. He said the weakness of China's currency had cost 500,000 US jobs.

Economists believe that an uneven playing field in trade between the world's two largest economies is slowing America's recovery from recession. Barack Obama this month dispatched his financial guru Larry Summers to Beijing in an effort to secure greater flexibility in the yuan, and the US president raised the issue personally with China's premier, Wen Jiabao, at last week's UN general assembly.

The congressional bill is more symbolic than truly practical – it would face opposition in the Senate and President Obama would be unlikely to sign it. Critics say it could inflame relations with China, which is notoriously prickly about explicit foreign criticism, and that tit-for-tat measures would hurt US companies already operating there.

The Chinese government promised a more flexible approach to its currency in June – but since then, the yuan has risen by only 2%. China argues that it has the right to adopt policies that support its rapid economic growth and help lift its citizens out of poverty.

Peter Morici, a former chief economist at the US International Trade Commission, said Chinese imports were reaching the US at less than the cost of the materials in them: "It's really a beggar-thy-neighbour policy [by China] that victimises trading partners."

Unions have pressed Obama to take a firmer line with China. Leo Gerard, international president of the USW steelworkers' union, said the weak yuan risked allowing China to dominate the emerging green technology sector.

"The failure to address China's practices means that we will never see the promise of green jobs," he said.