Final answer:
The Embargo Act of 1807 established a mechanism for suspending trade with British merchants in response to the harassment of American shipping and was designed to exert economic pressure on Britain and France.
Step-by-step explanation:
The act that established a mechanism for suspending trade with British merchants is the Embargo Act of 1807. This legislation was introduced in response to Britain's constant seizure of American ships and the impressment of American sailors into the British navy. By prohibiting American vessels from leaving U.S. ports, the Embargo Act aimed to exert economic pressure on Britain and France to respect American neutrality on the high seas. However, the act ended up causing significant economic hardship in the United States, and it was unpopular among American merchants and the general populace, leading to a decline in support for President Jefferson and his administration. It was not successful in its goals and ultimately had to be repealed.