U.S. companies and business groups are lining up to oppose the Trump administration's plan to slap tariffs on Chinese imports, as the two nations step up efforts to resolve their trade dispute.

About 120 firms and industry groups are scheduled to testify at a hearing beginning Tuesday on the administration's plan to impose tariffs on $50 billion in Chinese goods. So many groups signed up that the U.S. Trade Representative's Office extended the hearing by two days until Thursday. The USTR has received more than 2,700 comments.

The hearing coincides with a planned trip to Washington by Chinese President Xi Jinping's top economic adviser for broader trade negotiations. The visit is a follow-up to talks led by U.S. Treasury Secretary Steven Mnuchin in Beijing earlier this month, when they failed to bridge their wide differences.