U.S. Rep. Sean Duffy announced his resignation in a Facebook post Monday morning.
The congressman — who represents Wisconsin’s 7th District — was first elected in November 2010, and won his fifth Congressional term in November.
In his post, Duffy wrote after serving for eight and a half years, he was stepping down to focus on his family.
"Being away from home in Washington four days a week is challenging and for that reason, I have always been open to signs from God when it comes to balancing my desire to serve both my family and my country," he wrote.
Duffy and his wife, Fox News commentator Rachel Campos Duffy, are expecting their ninth child in October. Duffy said the child has been diagnosed with "complications, including a heart condition."
He said aside from marrying his wife, representing Wisconsin has been the "highest honor" of his life.
"Representing you — the people and families of Wisconsin’s 7th District — in Congress has been the highest honor of my life. Together, we have engaged in the most important battles of our time: protecting freedom of speech and religious liberty, taking care of our veterans, defending the unborn, and saving American jobs and American capitalism," he wrote.
Duffy will step down Monday, Sept. 23.