Republican Representative Jeff Fortenberry is resigning following his conviction on charges of lying to investigators about illegal foreign campaign donations.

Fortenberry was charged after denying knowledge of $30,000 in donations to his campaign from Gilbert Chagoury, a Lebanese-Nigerian billionaire, who had been accused of conspiring to make illegal donations to politicians in America.

“It has been my honor to serve with you in the United States House of Representatives,” the Nebraska congressman wrote in a letter to his colleagues. “Due to the difficulties of my current circumstances, I can no longer effectively serve.”