Two U.S. senators looking to crack down on the number of packages from China that enter the country duty-free are calling on President Joe Biden to take executive action, saying U.S. manufacturers can’t compete with low-cost competitors they say rely on forced labor and state subsidies in key sectors.

U.S. trade law allows packages bound for American consumers and valued below a certain threshold to enter tariff-free. That threshold, under a category known as “de minimis,” stands at $800 per person, per day. The majority of the imports are retail products purchased online.

Alarmed by the large increase in such shipments from China, lawmakers in both chambers have filed legislation to alter how the U.S. treats imports valued at less than $800. Now, Sens. Sherrod Brown, D-Ohio, and Rick Scott, R-Fla., have sent a letter to Biden calling on him to end the duty-free treatment altogether for those products.