Is there a term in US politics for when the President's party doesn't control (both chambers) of Congress?
The term is divided.
Divided government in the United States
In the United States, divided government describes a situation in which one party controls the executive branch while another party controls one or both houses of the legislative branch.
A divided government is a type of government in presidential systems, when control of the executive branch and the legislative branch is split between two parties, respectively, and in semi-presidential systems, when the executive branch itself is split between two parties.
Early in the 20th century, divided government was rare in the United States, but since the 1970s it has become increasingly common. Divided governments are contrasted by "government trifectas"—a different situation in which the same party controls both the executive and legislative branches.
In systems with a strong president and prime minister, such as in France, divided government is known as cohabitation. In cohabitation, executive power is divided between a president of one party and a cabinet of government ministers of another. Cohabitation occurs because of the duality of the executive: an independently elected president and a prime minister who must be acceptable both to this president and to the legislature.
A government trifecta is a political situation in which the same political party controls both the executive branch and the legislative branch in countries that have a legislative branch with two houses and have strict separation of powers. The term is primarily used in the United States.