Sigh. There they go again. Modern liberals just can't help themselves, it seems.

As polls showed the presidential contest tightening up early last week, worried Democrats began flogging the Americans-are-racists theme more openly than ever. John Murtha, the white Johnstown congressman, made the accusation local, while Deval Patrick, the Democratic, African-American governor of Massachusetts, used a campaign stop in Pittsburgh to make it international.

It was the bad pol/good pol routine. One politician accuses citizens of a grievous failing, the other asks them to prove they're not guilty by voting for his guy. No matter how much truth is in the charge, the Democrats' approach is a recipe for decades more of national immaturity.

Pennsylvanians are used to Jack Murtha's shoot-from-the-mouth style. He was at it again last week, opining in an interview with the Post-Gazette's editorial board, "There's no question that Western Pennsylvania is a racist area." Barack Obama would win, he predicted, but not in a "runaway," due to racism.

After Mr. Murtha's brash set-up, Mr. Patrick's appeal to vote-as-racial-atonement was delivered Friday via the unnamed overseas visitors he meets regularly. They range from foreign businessmen and heads of state, and they are "very, very interested in Barack Obama's candidacy," he said in a Post-Gazette story. "Once, I asked one why, and his response was so beautiful. He said, 'We are watching to see if America is who she says she is.' "

The American ideal is to vote for racial identity rather than political ideas? And that's beautiful? Really? Hmmm -- sounds both simplistic and predictably left-wing.

And which foreign nations might these be, eager to judge the American experience? The ones in Europe that keep their post-colonial, Muslim minorities as second-class citizens in roiling ghettos? The ones whose leaders openly make outrageous anti-Semitic remarks? The ones whose economies have been mired for years in the stagnation of nanny-state socialism?

Inquiring minds might like to know, but ultimately it doesn't matter. Whether America is who she says she is has already been settled: A man who is black and who proposes policies that are further left than any major-party candidate in American history has emerged as his party's choice for the highest office in the land.

The best thing that could happen on Nov. 4 is for like-minded people to give him their votes, regardless of their race or his, and for people who embrace free-market, limited-government principles to vote for his opponent, regardless of their race or his.

That said, to some unknowable extent, Mr. Murtha's accusation is both true and lamentable. There are still racists living in the United States, and some of them even live in Western Pennsylvania, which happens to be a Democratic stronghold.

Pennsylvania Gov. Ed Rendell, a Hillary Rodham Clinton supporter, made the same claim about the entire state back in February. Also while chatting with the Post-Gazette editorial board, he said, "You've got conservative whites here ... who are not ready to vote for an African-American candidate." (Note the tiresome Democratic smear of equating racism with conservatism.)

Mr. Rendell's comments came two months before the primary, but Mr. Obama's remarks about bitter small-town voters clinging to their guns and religion exploded into public debate 10 days before the primary. Mrs. Clinton won Pennsylvania by a margin of 10 percent.

Were the Democrats who voted for her motivated by racism, or were they turned off by Mr. Obama's disdain for their lives and values? Or did they just prefer her prescription for the country's future?

The same questions will still apply on Election Day. Republicans have won nine of the 15 presidential races since the end of World War II. Candidates of either party usually win by very slim margins. That's a strong enough pattern to assert that Americans are pretty evenly divided ideologically, are in general a little more conservative than the Democratic Party and like to invigorate the body politic regularly with a tonic of something completely different.

Colin Powell made a similar point in endorsing Mr. Obama yesterday morning, speaking of "transformational" effects and "generational change."

The last Democrat who won the White House also promised generational change. Bill Clinton's first two years on the job, with Democratic majorities in Congress, so reinvigorated the Republicans that Clinton's policies were forced to the center.

With this aspect of history set to repeat and play itself out over the next few years, Americans may be ready to relearn the truth that ideas, not skin color, are what really matter. That, in fact, is what makes America what she is.