The party or coalition of the two candidates that won the second highest vote within the state then assigns a senator to occupy the third seat (first minority seat), according to the list of candidates that the party or coalition registered with the Instituto Nacional Electoral (INE).

Senators serve six-year terms, running concurrently with the president of Mexico's sexenio.

Its internal government has two main instances, namely: To deal with legislative affairs, senators form commissions dedicated to a particular issue.

The most important committees are interior, constitutional issues, defense, finance, and justice.

During these breaks, the standing committee of the Congress of the Union is installed and serves as the legislature's depository.

It comprises 37 members — 19 deputies and 18 senators — appointed by their respective chambers the day before the closing of the regular sessions.