Barack Obama is a committed liberal, political phenom and, from all appearances, a genuinely nice guy.

But have you heard about Barack Hussein Obama? You know, the Democrat with the Muslim name (even though he's a Christian), and the Muslim father (who abandoned his family when Barack was a toddler)? The politician who went to Kenya and put on an Islamic-looking turban (never mind that American politicians abroad often don native garb out of respect)?

If you haven't heard that Barack Obama is the Muslim Manchurian Candidate, don't worry, you will. This smear is rampant on the Internet and even surfaced earlier this week in a conservative talk show host's remarks at a John McCain rally in Ohio. Sen. McCain rebuked the radio talker and was, in turn, slammed by Rush Limbaugh for being a girlie man.

Good for McCain, who suffered a more sophisticated smear when The New York Times recently floated rumors of an extramarital affair. Politics are a full-contact sport, but the gutter is out of bounds. Candidates should condemn would-be surrogates who sling slime on the side.

Not all questions about a candidate's character are off limits. For example, Obama has repeatedly distanced himself from the bigoted Louis Farrakhan, but the candidate's spiritual mentor, the Rev. Jeremiah Wright, is a big Farrakhan supporter. Wright is a figure of controversy because of his race-based theology, which supporters see as pro-black but critics see as anti-white. It's fair to ask Obama how he reconciles himself to his pastor's views.

What's unfair — and ugly — are the underhanded personal attacks and swirling, groundless innuendo. McCain set a good example this week by repudiating conservative bigmouths. Obama and Hillary Clinton should do the same when the mud comes from the left.

It's said that this fall's contest is going to be a "change election." Wouldn't it be grand change if, for once, the presidential candidates unambiguously took the high road?