An American senator has said that China must halt the flow of fentanyl ingredients into the U.S. before any trade negotiations, a demand that clouds the prospect of imminent leaders¡¯ talks to ease tensions between the world¡¯s two largest economies.

Steve Daines, a close ally of U.S. President Donald Trump, laid out the condition in meetings with Chinese officials in Beijing over the weekend. The Republican lawmaker said he hopes a leadership meeting will take place before the end of the year, although Trump previously said it would happen soon.

¡°It¡¯ll be difficult to have any conversation about tariffs and nontariff barriers until the fentanyl precursor issue is resolved,¡± Daines said in a telephone interview with Bloomberg News on Sunday.