The Trump administration has been discussing severe restrictions on medicines from China that, if enacted, could upend the American pharmaceutical industry and availability of everything from generic drugs to cutting-edge treatments.

At the heart of the possible clampdown is a drafted executive order that threatens to cut off the pipeline of Chinese-invented experimental treatments. Major pharmaceutical companies have been buying the rights to drugs created in China for cancer, obesity, heart disease and Crohn’s disease.

The prospect of the order, a draft of which was obtained by The New York Times, has set off furious behind-the-scenes lobbying efforts by two diametrically opposed groups — each with billions of dollars at stake.

Prominent investors and corporate executives with close ties to the White House, including the tech billionaire Peter Thiel, the Google co-founder Sergey Brin, the Koch family and staff at the investment firm run by President Trump’s son-in-law Jared Kushner, have argued for a decisive crackdown against what they view as an existential threat by China to U.S. biotechnology, according to four people briefed on their lobbying who asked for anonymity to discuss private conversations.

These investors have money at risk because they hold hard-to-sell investments in fledgling American companies that have been struggling to keep up with China’s surging biotech sector.

On the other side are the world’s largest drugmakers, including Pfizer and AstraZeneca. In the last few years, they have been on a shopping spree in China for low-priced experimental drugs, spurning smaller American biotech companies that are developing similar medicines.