Hunter pleaded guilty earlier this month to misusing $150,000 in campaign funds for his own personal expenses.
A federal prosecutor said he plans to ask for at least a year in prison .
The six-term Republican fought the allegations for more than a year. Hunter represents parts of Orange, Riverside and San Diego counties.
Hunter didn't give a specific date for his departure, and if he steps down after Jan. 1, he will take home a month's pay since members of congress are paid on the first day of the month.
This past week, Hunter pled guilty to a single campaign finance violation.
He was facing re-election next November.