By David Domke

Let's just call this the "fault lines" presidential election.

In geological terms, fault lines are locations where friction occurs between differing earth masses - and this friction can cause ruptures, earthquakes, upheaval. The San Andreas Fault in California is perhaps the best-known example of a fault line.

In political terms, fault lines are the demographic and psychological characteristics that often produce friction in a society. In the United States, the biggest fault lines tend to be race, gender, economic class, sexuality, religion, and age. These are lines along which political earthquakes and ruptures occur. And they are the lines upon which presidential elections often turn.

This presidential election now has virtually all of them, and they are coming to a head right here, right now.

Barack Obama on Thursday became the first African American to gain the presidential nod of a major political party, accepting the Democratic Party's nomination. This event took place before 84,000 people in open-air Invesco Field in Denver and 38 million more watching on television - more than watched the Olympic Opening Ceremonies two weeks ago, more than watched the Academy Awards this year, and nearly twice as many as watched John Kerry's nomination-acceptance address for the Democratic Party in 2004. That's what happens when history takes place.

What people saw in Obama's speech was a game-on, take-no-prisoners approach to presidential politics. It was exactly what Obama had not offered since hitting the national scene, and the speech hit a home run - wowing the liberal blogosphere, mainstream news media, and even Pat Buchanan, a former Richard Nixon aide who runs politically to the right of virtually everyone, who said this on MSNBC after the address: "It was a genuinely outstanding speech, it was magnificent ... It is the finest - and I saw [Mario] Cuomo's speech [in 1984], I saw [Ted] Kennedy in '80, I even saw Douglas MacArthur, I saw Martin Luther King - this is the greatest convention speech."

Obama can give a good speech, we know. But what put it over the top was something he drew from his new running mate, Joe Biden - a self-described scrappy kid from Scranton, Penn., who told the nation on Wednesday that when growing up, his mother told him to bloody the nose of any kids who bullied him. With the cameras trained on her watching in the crowd, Biden's mother smiled and said, Yep I did. It was a classic, Archie Bunker moment. Biden's speech had a simple, unspoken tagline: "Made in America."

Obama chose Biden for the VP slot to shore up Obama's lackluster appeal to working-class voters, particularly those who are white. Biden has immediately lit a fire under Obama, a fire that goes straight to the core of all of the millions of Americans who are worried about the economy and whether Obama can serve as commander-in-chief. John McCain's inability last week to identify how many houses he owns was like manna from heaven for the Democrats, and Obama and Biden have run with it.

It's in this environment that McCain one-upped everyone Friday morning, delivering the biggest blockbuster yet: naming Alaska governor Sarah Palin to be his VP running mate.

Palin has been governor of Alaska (the 47th-largest state in terms of population) for less than two years and has little foreign-policy experience, a reality which undercuts the McCain camp's criticisms of Obama's relative short tenure on the national scene. Further, Palin is virtually unknown to anyone outside Alaska or political-junkie circles. So what does McCain get with Palin that made her appealing as a partner? A couple things. Indeed, a couple crucial things.

First, Palin is a woman. This was a high-priority for McCain; NBC political news director Chuck Todd put it this way on air Friday morning: "They really wanted to pick a woman, and there were no obvious choices." The thinking is that Hillary Clinton's supporters in the Democratic Party are ripe to be pealed away from Obama. Some evidence suggests this window may be closing after the Democratic convention, but it's certainly possible. Picking a woman, particularly someone who has cast herself as a reformer, as Palin has, reinforces McCain's maverick image.

Second, Palin is well-liked among conservative white evangelicals in this country, who are the base of the Republican Party but have been less than enthused about McCain's candidacy. A Pew Research Center survey of U.S. adults released 10 days ago showed that McCain's support among these voters is comparable to George W. Bush's in 2004, but that there is an enthusiasm gap. In August 2004, 57 percent of white evangelicals said they "strongly" supported Bush; this August, only 28 percent said they strongly supported McCain. That's not a gap; that's a chasm.

Evangelicals like Palin's pro-life position on abortion, and her statement in the 2006 gubernatorial race that she supported the teaching of creationism in public schools was an explicit signal to these voters. On cue Friday, Richard Land, a key leader of the Southern Baptist Convention, declared, "Governor Palin will delight the Republican base." If these voters rally to McCain's side, the Palin selection will be a brilliant move.

On the potential downside though, McCain just made his age and health a key part of this election. He is a cancer survivor and turned 72 on Friday; he will be the oldest first-term president if he is elected in November. Democrats now have an opening to emphasize McCain's age and health, by asking whether Palin is fit to be president. The message of "One heartbeat away" is sure to become a talking point for Palin. Whether Palin is a genius pick or Geraldine Ferraro redux is the question of the hour.

The fault lines - and so many of them - have emerged. Next week it is the Republicans' chance to make their case to the American public. Two months until election night.

David Domke, a former newspaper journalist, is a professor in the Department of Communication at the University of Washington. His latest book, "The God Strategy: How Religion Became A Political Weapon in America," was published in January. He can be reached at domke@u.washington.edu.