The Justice Department announced on Friday that it intended to retry Senator Robert Menendez of New Jersey, two months after a jury deadlocked on federal corruption charges against him. The move means Mr. Menendez will have to defend himself again in a year when he is up for re-election.

A new trial for Mr. Menendez, a Democrat, who has been in the Senate for 12 years, adds a wrinkle to the political map in this year’s 2018 midterm elections. While the senator has not officially announced that he is running, he has given no indication he intends to retire.

Another politically damaging trial could put Democrats in the unexpected position of having to spend resources in New Jersey, a reliably Democratic state, in an election in which they are hoping to pick up seats and possibly shift the Senate back to Democratic control. So far, however, no strong Republican challenger has emerged.

Mr. Menendez’s office vowed on Friday to again fight the charges, but provided no indication about the senator’s political plans.