“Scots-Irish never accept the fact that their leaders are superior to them in any way, in terms of their human qualities,” Webb says. Instead, they measure their leaders by their own code of honor, loyalty and sometimes in-your-face leadership.

The states with the largest populations of Scots-Irish -- Alabama, Arkansas, both Carolinas, parts of California, Colorado, northern Florida, Georgia, Indiana, Illinois, Kansas, Kentucky, northern Louisiana, Mississippi, Missouri, New Hampshire, southern Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, West Virginia -- are a veritable list of what a candidate must carry in order to become president.

They also are the bulk of “red states” that Democrat Obama (Scots-Irish on his mother’s side) has carried in primaries and caucuses.

In modern politics, Republicans have done a better job of courting the Scots-Irish. With their traditional family ties, individualism, proud military service and disdain for too much government, the Scots-Irish have swung right ever since the civil-rights era.

Democrats began losing the Scots-Irish vote when they shifted to courting the black vote. That shift ended the Democrats’ hold on the South, where many Scots-Irish lived.

As a voting bloc, the Scots-Irish respond passionately to five things: the right to bear arms, the preservation of family, a love of country, a respect for life and success in war.

As leaders, they often deliver a populist message with a take-no-prisoners swagger. The best examples in presidential history are Andrew Jackson, Teddy Roosevelt, Ronald Reagan and Bill Clinton.

According to Webb, America’s “populist notion of a culture that demands strong leaders makes it a natural breeding ground” for leaders in the Scots-Irish tradition.

So it makes sense to him that all four of today’s candidates descend from “Born Fighting” clans.

Webb, a one-time Republican who switched sides in 2006 to run for the Senate, is on just about everyone’s shortlist for vice president.

And, yes, he too is Scots-Irish.