Abraham Lincoln was in a Senate race with Stephen A. Douglas and lost.
Abraham Lincoln . In 1858 , while taking part in a series of highly publicized debates with his opponent and rival , Democrat Stephen A. Douglas , Lincoln spoke out against the expansion of slavery , but lost the U.S. Senate race to Douglas . The Lincoln -- Douglas Debates ( also known as The Great Debates of 1858 ) were a series of seven debates between Abraham Lincoln , the Republican candidate for the United States Senate from Illinois , and incumbent Senator Stephen Douglas , the Democratic Party candidate .