Two senators decided Tuesday to delay a vote on a bill that would punish China for restricting its exchange rate, saying they had seen signs of currency reform during a recent trip to China.

The bill, sponsored by Sens. Lindsey Graham, R-S.C., and Charles Schumer, D-N.Y., would impose 27.5 percent tariffs on Chinese imports if the currency dispute is not settled.

The lawmakers said they would delay a vote to Sept. 29 at the latest. They said they would call the bill up for a vote if the pace of currency reform slowed before then.

"The jury is still out," Graham warned. "We will see in the next six months what the verdict is."

Schumer told reporters they "believe that the Chinese see the fact that manipulating their currency cannot continue."

"We expect continued progress on this issue," he said.

U.S. lawmakers want China to take steps to allow the yuan to strengthen against the dollar, saying the currency is undervalued by up to 40 percent.

The undervalued currency, U.S. manufacturers and politicians say, gives Chinese exports an unfair trade advantage, contributing to the United States' record $202 billion trade deficit with China last year.