His problem, they say, is that some voters don't like him because he's black. Or they don't like his policies because they don't like having a black president.
So, you see, if you don't like Obamacare, it's not because it threatens to take away your health insurance, or to deny coverage for some treatments. It's because you don't like black people.
This sort of thing seems to be getting more frequent, or at least more open. As White House Dossier writer Keith Koffler notes, HBO host Bill Maher accused Internet tyro Matt Drudge of being animated by racism because he highlights anti-Obama stories.
MSNBC's Chris Matthews asked former San Francisco Mayor Willie Brown if House Chairman Darrell Issa's treatment of Attorney General Eric Holder was "ethnic." Brown agreed, and Matthews said some Republicans "talk down to the president and his friends."
There's an obvious problem with the racism alibi. Barack Obama has run for president before, and he won. Voters in 2008 knew he was black. Most of them voted for him. He carried 28 states and won 365 electoral votes.
Nationwide, he won 53 percent of the popular vote. That may not sound like a landslide, but it's a higher percentage than any Democratic nominee except Andrew Jackson, Franklin Roosevelt and Lyndon Johnson.
Democratic national conventions have selected nominees 45 times since 1832. In seven cases, they won more than 53 percent of the vote. In 37 cases, they won less.
That means President Obama won a larger percentage of the vote than Martin Van Buren, James K. Polk, Franklin Pierce, James Buchanan, Grover Cleveland, Woodrow Wilson, Harry Truman, John Kennedy, Jimmy Carter and (though you probably don't want to bring this up in conversation with him) Bill Clinton.
Now it is true that you can go out in America and find people who would just never vote for a black person. But it's a lot harder than it was a generation or two ago, when most voters admitted to pollsters they would never vote for a black president.
And you can probably find some people who usually vote for Democrats but would not vote for a black Democrat. But not very many of them, and they're likely to be pretty advanced in age, and so there are likely fewer of them around than there were four years ago.
My own view is that such voters were more than counterbalanced by voters who felt that, as an abstract proposition in the light of our history, it would be a good thing for Americans to elect a black president.