Illinois Sen. Mark Kirk (R) announces his bid for reelection in 2016. (Mark Kirk via Youtube)

Want to see a terrific political ad? Spend 60 seconds watching the commercial above -- the first of Illinois Sen. Mark Kirk's (R) 2016 reelection bid that began airing today.

The ad tells the story of a stroke Kirk suffered in early 2012, barely two years after he was first elected to the Senate.  Kirk recounts how he had to learn to walk again as images of him doing just that are shown on screen. "I forced myself to climb up steps every day -- even up our tallest buildings," he recounts. "I was determined to return to the Senate to do the job you elected me to do."

The ad closes with Kirk reaching the top of the steps leading to the U.S. Senate -- and being greeted by Vice President  Biden and Senate leaders Harry Reid (D-Nev.) and Mitch McConnell (R-Ky.) -- while the text "Bipartisan Leaders Welcome Senator Kirk's Return" appear on screen.

"I climbed the [Senate] steps for everyone facing their own challenges," Kirk says in the closing line of the ad.

There's a lot going on in this ad  -- and most of it is very good, politically speaking.

The ad is, first and foremost, an acknowledgment by Kirk and his campaign that his stroke and ongoing recovery is not the sort of thing that he could just ignore.  It's an admission that, no, the Kirk that got elected in 2010 isn't exactly the same Kirk running for a second term in 2016. But  it is also a powerful attempt to own that story and frame it in a way that is beneficial to Kirk's political future.  What Kirk is saying -- although he never says it directly in the ad -- is: "I got hit with something pretty bad. But I fought back. I can still do the job. And now I understand even better what it's like to be faced with serious obstacles -- whatever they may be -- in life."

That's moving stuff -- whether or not you are a Republican.

Which brings me to my second point. To win next November, Kirk needs to win lots of votes from people who consider themselves Democrats. In 2012, Barack Obama, who, granted, had hometown ties to Chicago, won Illinois by 17 points after winning the state by 25 in 2008.  Kirk, running in a great election cycle for Republicans in 2010 against a corruption-stained Democratic candidate, barely won 48 percent to 46 percent -- a margin of roughly 60,000 votes out of more than 3.4 million cast.

Those raw numbers are why it's so important that Kirk's ad never mentions that he's a Republican and ends with an image of him being greeted by Biden and Reid. The less Kirk is associated with his national party, the better his chances are at winning.

To be clear: This ad, as good as it is, doesn't change the fact that Kirk is the most endangered Senate incumbent in 2016. The dynamics of the state coupled with the fact that he will likely face off against Rep. Tammy Duckworth, who has a very compelling personal story of her own, make this a very tough contest for Kirk to win. But, this ad suggests that Kirk understands the enormity of his challenge and is taking the right (only?) path available to him.