Mitt Romney's choice of Rep. Paul Ryan as his running mate was supposed to turn the campaign debate to economic issues. But over the weekend, I found myself stuck in the same old conversation - directed by the Democrats.

I follow @BarackObama on Twitter. The first messages I received about Ryan were these: "FACT: Paul Ryan would ban all abortions, even in cases of rape or incest." "FACT: Paul Ryan cosponsored a bill that would ban many common forms of birth control, including certain birth control pills." "FACT: Paul Ryan voted against the Lilly Ledbetter Fair Pay Act, which helps women fight for equal pay for equal work."

Ryan's positions make my blood boil, but in an economy in this much trouble, how could I possibly choose a ticket based on his stand on women's issues?

A quick look through the other tweets from @BarackObama early Saturday showed the Democrats playing additional divisive identity politics. Ryan would cut Pell Grant scholarships, one said, and would turn Medicare into a voucher program.

That covers women, students and seniors - all targeted voters in the fall.

The problem with this kind of politicking is its appeal to tribal factions. It courts our perceived identities - gender, race, age, sexual orientation - rather than encouraging healthy debate.

Identity politics can be insulting. Analysts talk about "the Jewish vote" and "the white ethnic vote" as though members of groups always vote on single, specific issues that are apparent on the surface.

That's clearly not the case. For example, the Pew Hispanic Center notes that Hispanic voters have consistently ranked immigration issues fourth or fifth. In a 2011 survey of such voters, jobs, education, health care, taxes and the federal budget deficit - issues that are of concern to all Americans - ranked higher.

It's astonishing to witness a sitting president push the identity buttons, as though he's given up calling for unity, the common interest and the greater good. Wait a minute. Weren't those the themes of Campaign Obama 2008?

To be sure, politicians have always appealed to identity to build coalitions, and the Democrats have done so with some historic success. But Obama's promise was to help us rise above the tribalism.

Romney-Ryan would like to make this election a referendum on the economy, with 23 million Americans unemployed or underemployed, and that's a risky arena for Obama. No president since World War II has won re-election with unemployment topping 8 percent for all, as it does now, and it's higher among blacks and young people, who turned out enthusiastically for Obama in the last election. The rate stood at 7.5 percent when Jimmy Carter lost.

I believe that Obama has done as well as any president might have, faced with the enormous challenges of the last four years. And it would be a mistake to return to a governing philosophy that favors the wealthy and frees big banks from sufficient regulation. But distracting voters is a bad alternative to debating how we emerge from this funk. What's more, playing up identity politics guarantees an ugly campaign, one filled with more than the usual innuendo and smears. It divides Americans into warring groups. It sends us into a defensive crouch.

This kind of politicking makes it hard to govern after the election. What does an economically depressed country look like after it weathers a mean and sordid presidential race? We may find out.

Instead, we could use a little morning in America right now - a little vision. Where's the spirit of @RonaldReagan when we need him?

This essay was first published in Newsday.