Who Said This?

[Gene C]

My first guess would be Benjamin Butler ?

[RJNorton]

John Parker Hale?

[Amy L.]

No, not Benjamin Butler, but a figure who also argued for the impeachment of Andrew Jackson. (So his political party is clear, and that he held office following Lincoln's Administration is inferred.)
And not John Parker Hale.
(I gotta look up who these people are...)

[AussieMick]

Thaddeus Stevens?

[Amy L.]

Less famous than Thaddeus Stevens.
A lawyer who sought and won a seat that Lincoln curiously never sought. (And served in three of the seats that Lincoln did pursue.)

[Amy L.]

Gene had suggested Elihu Washburne, but no, it was not from Mr. Washburne, although on the right track - A representative from Illinois.

You know, the quoted elected official was a Big Wig, with a busy schedule and lots of responsibilities - Still, he was one of several representatives to personally deliver "hospital supplies to the succor of the wounded." (And got points from the Electorate for his good deed.)

[RJNorton]

Jesse Olds Norton?

[Amy L.]

No, not Jesse Olds Norton.
I'm running out of clues!
Just to review, what we know:
A lawyer and Representative who eventually turned Republican.
He visited the White House some time during the Civil War.
He held seats in (at least) the Illinois House of Reps, Congressional House of Reps & the US Senate.
(oh, oh, to clarify, he was Rep for a different district in the House of Reps, not the 6th)

Another clue: He was succeeded by Richard Oglesby

Admittedly, I wouldn't have gotten as far as y'all have.

[RJNorton]

Richard Yates?

[Amy L.]

Mister Richard Yates! Yes, Roger!
My source: Terry's KY History