Editor's Note: John McCain died Saturday at age 81.

Dear Senator McCain,

The news of your imminent departure comes as no surprise given what we know about the disease that is taking you from us. And yet, it still hits on my heart like a ton of bricks.

Not just because of the depth of my respect, reverence and love for you. But because it is dawning on me just how much your voice, clear conscience and moral authority will be missed in the American political arena. There simply is no other John McCain to take your place.

It was the honor of a lifetime to work for you. You always said we should serve a cause greater than ourselves. Thanks to you, for a brief period I did that.

I had come from Bush world, and the team that denied you the presidency. But you never held that against me.

We bonded in the green room of the last presidential debate in 2004, when you hosted President Bush and his team. While we all milled around, I noticed a news story on the television about the selfless soldier Pat Tillman who had left the NFL and a huge salary to serve in the military, and had been killed by friendly fire. His former teammate Jake Plummer had sewn his number onto his jersey in remembrance. The NFL commissioner had come down hard on him, fining him and forcing him to remove the patch. In the news clip, you went off on the commissioner and gave him a classic McCain acid bath.

I approached you, and said, “Senator, I just saw this, and wanted you to know I appreciate what you said. I too am a huge fan of Pat Tillman. So much so that after he died, I wanted to make sure I thought of his sacrifice often. And to ensure that I didn’t forget, I had his number, 40, tattooed on my shoulder.”

You said: “That’s bullshit, McKinnon.” So I stripped down in the middle of the green room. And when you saw the evidence, you teared up, hugged me, and said, “I knew there was a reason I liked you, McKinnon.”

When you asked me to work for your presidential campaign a few years later, I said “Senator, I’ll go mow your lawn in Sedona if that’s what you want.”

I had one caveat. I had met Senator Barack Obama and though I disagreed with much of his politics, I liked him and thought his candidacy would be good for the country. So I told you that, as unlikely as it seemed in early 2007, that I would step out if you and him ended up running against each other in the general election. I just didn’t want to be the tip of the spear attacking Obama, and didn’t think I would be the right person under the circumstances.

I think you thought it odd, but assented, particularly because you didn’t think it would happen. To make sure you remembered, I wrote a memo to the senior staff of the campaign outlining the agreement.

Then I saddled up, and stayed there when the campaign melted down and most of the staff left. There were just a handful of us left, working for free.

Candidly, I stayed on as volunteer not so much with the notion that you could still win the nomination but simply because I respected you so much and wanted to help regain some of the dignity that had been lost due to the humiliating circumstances of going from well-funded, can’t-lose front runner to flat-broke also-ran who’d come in third to Mike Huckabee in Iowa.

Those of us who remained were with you as you marched through New Hampshire, completely broke. I remember staying at the cheapest possible hotels, some of them literally under construction.

And then it happened. You won the nomination. You caught lightning in a bottle through your sheer determination and inspiring message of “Country First.”

And sure enough you had forgotten our deal. So, I brought you the memo. And in classic McCain style, you didn’t get angry, you hugged me and said:

“Thanks for helping me get here. It would be very un-McCain-like not to keep my word, so God bless you and good luck.”

I want you to know, that was one of the hardest things I’ve ever done in my life.  To walk away after all the moments from the campaign that I remember and cherish.

We were flying in a small plane that hit some turbulence, and I was showing some white knuckles. Now most people know about your POW experience, but they don’t know that you ditched other planes. And in one horrific experience, you were in your plane on the deck of the USS Forrestal when a missile went off accidentally from another plane and hit yours. Your plane exploded and you jumped off the wing onto the deck. The fire engulfed the ship, and 134 people were killed. And yet, even though it was your plane that was directly hit, you somehow survived.

So, when I looked pale in the turbulence, you turned to me and said: “McKinnon, don’t worry about it. If you’re flying with McCain, you’re not going to die in a plane.”

But the moment that moved me most was the first time I went out on the trail with you. Because of your lean staff at the time, I was doing everything. Whoever had been with you before I showed up handed me a black bag. I looked inside and saw some basic grooming tools, like a hairbrush. But it was only when we arrived at our campaign stop that I realized the purpose.

We were in a van. And we walked out on the side away from the waiting crowd. And you turned to me, a decorated prisoner-of-war survivor, and bent over at the waist in supplication. And then it dawned on me:

You could not comb your own hair. Because of your arms being repeatedly broken as a POW, you could not raise your arms above your shoulders. Then you turned into the crowd. I turned away with tears in my eyes.

In the coming days there will be countless tributes to the brave political stands you took over the years. Your independence was legendary. While I didn’t always agree with you, there was never a question in my mind that you always did as you pledged you would and indeed put country first.

Though no one can or will take your place, I hope that as the country pays tribute to your incredible legacy others will be inspired to step up and try to be the next John McCain.

Gratefully Yours, McKinnon