Are you sitting down?

Because -- surprise! -- John McCain wants to run for reelection to the United States Senate in 2016.

When Kelly O'Donnell, above, wondered if it might be "worrisome" for some voters that the Arizona Republican would embark on another six-year term at age 80, McCain replied:

I say "watch me"; I say "watch me!" Take a look. Take a look at my eighteen-hour days.

Eighteen-hour days? Really? That only leaves six hours for sleep. When does McCain find time to do anything else?

Take a look at the hearings we have. Take a look at my legislative accomplishments. Take a look at all those Sunday shows I do.

(I added that last one.)

Now, I have to admit, this guy looks really, really good for 78. And I don't doubt for a second that he'd function just fine well into his eighties.

But, really, shouldn't John McCain have retired a long time ago? Like, after he lost to George W. Bush in 2000?

Let's face it: his career just hasn't been the same since. Increasingly erratic, McCain has become something of a bitter old crank.

It started when the Arizona senator opposed the tax cuts passed by the president of his own party (my emphasis):

On May 26, 2001, speaking on the Senate floor, McCain said, "I cannot in good conscience support a tax cut in which so many of the benefits go to the most fortunate among us, at the expense of middle-class Americans who most need tax relief."

McCain was one of only two Republicans to vote against President Bush's $1.35 trillion, 10-year tax cut. Two years later, in May, 2003, McCain was just one of three Republicans to vote against additional Bush tax cuts because, he said, the cost of the Iraq war was not yet known. He later told a Wall Street Journal reporter that he opposed the 2003 tax cut because it was "too tilted to the wealthy."

Now, while I would like to believe it was indeed McCain's "good conscience" that made him vote that way, I'm more inclined to think it was just good old-fashioned sour grapes.

Then there was his disastrous campaign for president in 2008 in which McCain lost to the first black candidate, a freshman senator whose middle name was "Hussein" and last name rhymed with "Osama." And all the while "putting country first" by cynically picking a certain half-term governor from Alaska as his running mate (for which he has yet to apologize).

After losing again, was McCain any more gracious in defeat? Hardly. He's been a thorn in the president's side ever since. Most recently, McCain was one of 47 Republican senators to put his signature on a letter to Iran's leaders about the nuclear talks. Even the junior senator from his own state, Jeff Flake, had the good sense to take a pass. "I just didn't think it was appropriate," he told The Arizona Republic.

And, finally, let's not forget all the countries that McCain would like to go to war with: Libya, Egypt, Syria, Iran and possibly North Korea and even Russia! (Am I leaving any out?)

Listen, I'm just gettin' started.

That's what I'm afraid of.

The man who could have retired as a statesman in 2000 has now become a . . . senator. Is there a better argument than John McCain for term limits?