Man, is this ever an interesting month for campaign memos. First Mike Henry’s missive about Hillary skipping Iowa and now this little bombshell from McCain adviser Mark McKinnon (hat tip: Political Wire).

The casual reader might wonder why strategists put their names on documents that, if made public, could eventually hurt them or their client’s standing. Reasons vary, but ultimately internal memos should have something to do with the candidate winning.

Speculation abounds John Mercurio at Hotline is a leading proponent) that Henry’s memo was leaked on purpose to lower expectations, but let’s assume that it was in fact a legitimate memorandum. Henry might have been tasked with the responsibility in the campaign or he might have long been the main proponent and was the victim of an internal fight over strategy.

But McKinnon’s memo is something all together different. He basically gave notice that he won’t help his client win if he faces a certain opponent.

McKinnon wrote that while he opposed Obama’s policies, especially on Iraq, he felt that the Illinois senator–as an African-American politician–has a unique potential to change the country. Therefore, McKinnon argued, he wanted no part in any efforts to tear down Obama’s candidacy.

Say what you will about Henry’s memo damaging Clinton, at least it advocated for a way to win the Iowa Caucus. McKinnon is laying down a marker that says “I won’t help if you run against him.” That essentially tells donors that one of McCain’s top advisers isn’t 100% on board with his campaign. It also signals to independents (and reporters) that Obama is a guy who crosses party lines.

True or not, that’s not a strategist’s job. It’s to help your client win. Henry’s name to paper makes sense; McKinnon’s does not.

Have PoliticalMavens.com delivered to your inbox in a daily digest by clicking here