Lyman Trumbull, the man to the left, was an integral member of the Lincoln election effort. He was also pretty impressive in his own right.
After living south for some time in his youth, where he learned to abhor slavery, he came to Illinois as a young lawyer. He met all the usual suspects--Lincoln, Lamon, Davis, Judd, et al--and his specialty on the legal circuit was civil rights cases.
He worked his way up the political ladder until he became senator for Illinois as a Republican. He worked beside Davis and Judd to get Lincoln nominated, throwing his considerable political muscle into the mix.
He returned to Washington, serving as senator during the War, and was instrumental in helping to craft and pass every piece of legislation that helped the newly-freed slaves, including the Thirteenth Amendment.
Alas, he had the nerve to vote against impeaching Johnson. This ended his political career, and the Republican Party considered him untouchable. He returned to Illinois, went back to practicing law, and fought the good fight until his death, in 1898.