J. Jennings Moss writes: The word came early Saturday morning. Joe Biden, a 36-year veteran of the Senate from Delaware, would be Barack Obama's running mate. Biden had run twice before for the presidency--the first time, in 1988, his bid was derailed by a plagiarism charge; the second time, in this cycle, he dropped out early from the pack of Democrats from which Obama rose.

Now Biden, a lawyer whose professional life has been largely spent in Washington, gets a shot to move down Pennsylvania Avenue (albeit to an office in the Old Executive Office Building rather than the White House, but it'll do).

Why Biden for Obama? It's certainly not to gain some kind of electoral vote advantage (Delaware only has three to offer). Nor is it an attempt to boldly craft a ticket like no other (the first African-American party nominee could have sent shock waves through the chattering class by tapping his primary rival Hillary Clinton). And it had nothing to do with Wall Street (A lawyer and career public servant from Illinois picking a lawyer and career public servant who would love to see George Bush's tax cuts on the richest Americans rolled back).

Obama undoubtedly saw Biden's expertise in world affairs--he's been on the Senate Foreign Relations Committee for three decades and became its chairman in 2006--a huge asset in a troubled world. Biden voted to authorize President Bush's initial move against Iraq, a decision he later regretted as he called for the removal of most U.S. troops from Iraq by this summer. Biden's stock likely rose for Obama when Russia launched its military assault against Georgia. With the world such a dangerous place, Obama needed a running mate who wouldn't need a training manual in international crisis.

A review of campaign contributions done by the Center for Responsive Politics shows that Obama and Biden have similar attitudes toward political action committees (they don't like them). The industries that have given the most to Biden are lawyers/law firms ($6.6 million), real estate ($1.3 million) and retirees ($1 million), according to the analysis at the center's OpenSecrets.org. While Obama has been critical of contributions from lobbyists, Biden has easily accepted dollars from employees of lobbying firms.

And Obama might have seen a political value to Biden's Catholic faith. The Democrats are responsible for the nation's only Catholic president, John F. Kennedy, but the party failed to elect a second Catholic when John Kerry ran against an incumbent President Bush in 2004. In the new book Left at the Altar: How the Democrats Lost the Catholics and How the Catholics Can Save the Democrats, Michael Sean Winters argues that Catholics joined forces with the Democrats in the 1930s, a coalition that served them well until Jimmy Carter's presidency. Since then, the party would lose five of the next seven elections.

In a review of Winters' book in the September issue of Condé Nast Portfolio, Roger Lowenstein notes that what distinguishes modern Democrats from their fathers and grandfathers is that they focus on the rights of the individual as opposed to the welfare of the group. "It is this un-Catholic vision that Winters says has led to the party's downfall. Regrettably, Winters targets Kennedy as a primary culprit. By promising to keep (his) religion out of the White House, Winters argues, Kennedy in effect authorized Democrats to abandon morality."

Will Biden be a new-old kind of Catholic running for the second highest office in the land, or will he be an old-new kind of Catholic candidate? It's hard to say as Biden, a man never at a loss for words, even when they trip him up, talks about both individuals and the group welfare. What he doesn't seem to talk much about, however, is big business.

In a New York Times column this week titled "Hoping It's Biden," David Brooks described the senator as being a "lunch-bucket Democrat" who was born to a rich family that saw its fortune disappear because of bad personal and business decisions.

Biden's father raised his son "with a fierce working-class pride -- no one is better than anyone else," Brooks wrote. "He has disdain for privilege and for limousine liberals -- the mark of an honest, working-class Democrat. Democrats in general, and Obama in particular, have trouble connecting with working-class voters, especially Catholic ones. Biden would be the bridge."

In the end, what Obama got more than anything with his choice as No. 2 is a kindred spirit with solid credentials.