What I said was in response to the House impeachment managers’ argument, which was that any action by a politician motivated in part by a desire to be reelected was, by its nature, corrupt. In my response, I listed three broad categories of relevant motive:
1) Pure national interest (help the military);
2) Pure corrupt motive (obtain a kickback);
3) Mixed motive (help the national interest in a way that helps a reelection effort).
I said that the third motive was often the reality of politics, and that helping one’s own reelection effort cannot — by itself — necessarily be deemed corrupt. I gave, as an example of mixed motive, President Lincoln’s decision to send Indiana troops home from the battlefield so they would vote for his party in a state election. He genuinely believed that his party’s victory in Indiana was essential to the war effort, but he also knew it would help him politically.