You may, from time to time, hear the 2008 presidential election referred to as "historic" by both candidates and pundits, without an explanation of why.
Some of the reasons you probably know: Barack Obama would be the first African American president, Hillary Clinton the first woman and John McCain the first veteran of the Civil War since William McKinley.
I kid, of course, but McCain, at 72, would indeed be the oldest first-time taker of the oath of office.
But there is another reason this election will be historic no matter who wins: it will be only the third time ever, and the first time in almost 50 years, that a sitting United States senator will ascend to the presidency.
McCain once quoted a friend who told him, "If you're a United States senator, unless you're under indictment or detoxification, you can automatically consider yourself a candidate for president of the United States."
In every election since I have been drawing breath, senators have made runs at their parties' nominations.
Some have succeeded John Kerry in 2004, Bob Dole in 1996 but none have been elected since John F. Kennedy edged out Richard Nixon in 1960.
Why do senators 100 of the most elite leaders in Washington, any number of which do indeed have presidential aspirations do so poorly in general elections?
Why has it taken so long to get one in office? As usual, I have some thoughts.
Senators are not executives.
The president is the chief executive of the federal government, a massive institution with a budget larger than the gross domestic product of most industrialized countries. We want to see the president as a decisive leader, a person who knows how to run an operation and isnt afraid of being the boss.
State governors fared much better than any other type of politician during presidential elections in the last century.
One reason is that governors do most of the same things that presidents do, only on a lesser scale: run day-to-day administrations, appoint officials, preside over cabinets, sign and veto legislation, and manage budgets.
Sitting vice presidents, even if we dont count those who ascended to the presidency without being elected, have also fared better than senators for similar reasons.
The vice president has executive branch experience, and if he is young enough and in good health (sorry, Dick Cheney), has probably been preparing for the job already.
Senators have visible track records.
A senator's body of legislative work is easily assembled and scrutinized. Opponents emphasize bills a senator voted for, those he voted against and times he didn't vote at all.
The Bush campaign in 2004 got a lot of mileage from calling Kerry and running mate John Edwards the first and third most liberal members of the Senate , based on voting records; meanwhile, all three surviving candidates in 2008 have been criticized by opponents for missing floor votes while campaigning.
Sponsorship of legislation is just as important. Until he began sweeping his opponents in early primaries, McCain was bitterly opposed by a large faction of the Republican Party for his stewardship of the McCain-Feingold campaign finance bill, which conservatives despise (This is especially interesting since McCain's campaign was pronounced dead last summer because it had no money).
Senators represent their constituencies at the expense of others.
This is not always true, but the important thing is the perception that senators are the ultimate practitioners of pork barrel politics.
In West irginia, Robert C. Byrd's name is imposed upon every project to receive a federal dollar, and in Alaska, Ted Stevens' "bridge to nowhere" represents the worst of American patronage.
We may not like it, but this is the way things get done. "Vote-trading" might be an appalling concept to everyone who would like to believe a good bill will pass on its merits and a bad bill will fail on its lack of them.
But log-rolling, back-scratching, trade-offs and compromise are things that simply must happen for a body of one hundred strong-willed, politically-connected individuals to ever accomplish anything.
Still, the negative public perception of this style of politics puts senators in a tough position among fickle voters.
Of course, being a senator is a pretty sweet job. It comes with power, prestige, money and a bully pulpit second only to the White House, with half the burden.
With all of the challenges they face, perhaps the surprising thing is not that more senators aren't elected president, but that so many of them even try.