WASHINGTON — A coalition of senators from both parties banded together Tuesday to offer a bill that’s aimed at pressuring China to stop manipulating its currency — a move that could boost manufacturing in places like Buffalo.

The bill would impose stiff new penalties on countries that artificially hold down the value of their currency, as China is widely seen as having done. The senators said China’s policy has made Chinese products far cheaper in the U. S. than they otherwise would have been, thereby reducing sales of competing American products.

The legislation also includes tariffs and a ban on U. S. government contracts going to companies located in countries that manipulate their currency.

“We are sending a message to the Chinese government: If you refuse to play by the same rules as everyone else, we will force you to,” said Sen. Charles E. Schumer. D-N. Y., one of the measure’s lead sponsors.

Schumer and Sen. Lindsey Graham, R-S. C., sent that message once before, introducing a similar measure in 2005 that passed the Senate with 67 votes before stalling in the House.

The lawmakers credited that effort with pressuring China to briefly stop artificially controlling its currency, the yuan, or renminbi. China allowed the yuan to float — and thereby increase in value by 21 percent, between 2005 and 2008, Graham said, though the exchange rate has remained frozen since then.

The senators said they were trying to find a way to get their legislation attached to a must-pass bill sometime in the next few weeks. They predicted the bill would be popular in the House as well at a time when the unemployment rate hovers near 10 percent.

White House spokesman Robert Gibbs refused to comment on the legislation, but Graham noted that President Obama has been decidedly less tough on China than he was during his 2008 campaign.

“When it comes to China, we campaign one way and govern another,” Graham said. “That has to stop.”

The bill could put the Obama administration in a delicate position because China is one of the main financiers of the nation’s record budget deficits.

Earlier this week, Chinese Premier Wen Jiabao said there was no reason for China to change its currency policy because he doesn’t “think the renminbi is undervalued.” U. S. arguments on the exchange rate are “groundless,” Ministry of Commerce spokesman Yao Jian said Tuesday at a briefing in Beijing.