At the regular election held in any State next preceding the expiration of the term for which any Senator was elected to represent such State in Congress, at which election a Representative to Congress is regularly by law to be chosen, a United States Senator from said State shall be elected by the people thereof for the term commencing on the 3d day of January next thereafter.
2 U.S. Code § 1.
Election to be certified by governor
It shall be the duty of the executive of the State from which any Senator has been chosen to certify his election, under the seal of the State, to the President of the Senate of the United States.
2 U.S. Code § 1a
Countersignature of certificate of election
The certificate mentioned in section 1a of this title shall be countersigned by the secretary of state of the State.