"It has been a tremendous honor to serve the people of Western New York. I regret the harm that my actions have caused my family, my staff and my constituents. I deeply and sincerely apologize to them all. I have made profound mistakes and I promise to work as hard as I can to seek their forgiveness.
"The challenges we face in Western New York and across the country are too serious for me to allow this distraction to continue, and so I am announcing that I have resigned my seat in Congress effective immediately."
A resignation triggered by a sex scandal could conceivably make for a competitive special election, though at this point it is obviously far too early to know for certain.
Lee was first elected in an open-seat race in 2008, winning by a margin of 55%-41%. His district voted for John McCain by 52%-46%, down from a 55%-43% vote for George W. Bush in 2004.
In the Republican year of 2010, Lee was easily re-elected by 74%-26%.