WATCH LIVE: Polls close in PA-18 special election
Marine veteran and former federal prosecutor Conor Lamb speaking at Democrats' nominating convention. Photo via the Pennsylvania Democratic Party.

Balloting has concluded in the special election for the Pennsylvania congressional seat vacated when Republican Tim Murphy abruptly resigned after reportedly asking his mistress to abort her pregnancy.

Republican state Rep. Rick Saccone is facing off against Democrat Conor Lamb, a former assistant U.S. Attorney.