U.S. Republican presidential candidate Mitt Romney's tough rhetoric on the Chinese currency issue is not in line with facts and would harm the important China-U.S. ties, a leading U.S. newspaper said Wednesday.

During Monday's presidential debate with U.S. President Barack Obama, Romney doubled down on his pledge to label China a "currency manipulator" on day one of his presidency if elected.

"Like the dog that catches the bus, the puzzle is what he would do on day two," the Wall Street Journal said in an article.

Romney was pushing the anti-China rhetoric over the objections of many advisers, and he seemed sincerely to believe that getting tough will yield concessions from Beijing, said the newspaper.

"Our own view is that Mr. Romney is underestimating Beijing. Even if Chinese leaders agree with his assessment of their economic interests, for domestic political reasons they can't afford to be pushed around by a hectoring U.S. President," added the article.

Torpedoing the bilateral relationship because of an ill-advised campaign promise could have multiple unforeseen consequences, warned the newspaper.

The currency issue is particularly misguided. Obama was correct that the Chinese yuan has already appreciated significantly. "Now the market is signalling that the currency is close to being fairly valued," noted the article.