Rep. Tom Marino, R-Pa., announced his resignation on Thursday with the longtime lawmaker saying he was taking a job in the private sector.
Marino, who was re-elected in November to a fifth term in the House, said that his last day in office will be Jan. 23.
"Having spent over two decades serving the public, I have chosen to take a position in the private sector where I can use both my legal and business experience to create jobs around the nation," Marino said in a statement.
He added: "I want to thank the people of the 12th Congressional District of Pennsylvania for the faith they have placed in me to represent them in Congress. It truly has been one of the greatest honors of my life.”
It is unclear when Pennsylvania Gov. Tom Wolf will hold a special election to choose Marino’s successor. In April, Wolf had 10 days to set a date for a special election after Congressman Charlie Dent resigned from Pennsylvania’s 15th Congressional District.
The 66-year-old Marino is a former county and federal prosecutor who co-chaired Donald Trump's successful presidential campaign in Pennsylvania.
Trump nominated Marino in 2017 to become the nation's drug czar, but Marino withdrew his name after reports alleging he played a key role in weakening federal power to stop companies from distributing opioids.
Marino has survived multiple bouts of kidney cancer.
With Marino’s exit, the Keystone state’s Democrats will hold a one seat advantage over Republicans. The state is currently evenly split between Republicans and Democrats after the latter picked up three seats in November’s midterm elections.
Fox News Chad Pergram and The Associated Press contributed to this report.