February is African American History Month. Yet these are days of sadness.

The brilliance of hope, so blinding a few short years ago, has dimmed. The dreams of a 21st-century America, where achievement is based on skills, determination and merit, free from an arbitrary color standard, have been replaced with injuries inflicted by present-day haters as malevolent as some of our worst enemies of the past.

Who could have imagined a U.S. publication suggesting that Israel “give the go-ahead for U.S.-based Mossad agents to take out a president deemed unfriendly to Israel in order for the current vice president to take his place.” In case you were unsure of what you’d just read, the writer clarified, “Yes . . . order a hit on a president in order to preserve Israel’s existence.”

Those words were written only a few weeks ago, in a column by the owner and publisher of the Atlanta Jewish Times, a weekly newspaper that dates back to 1925. Andrew Adler’s call for President Obama’s assassination was immediately condemned by major Jewish organizations. He apologized, resigned from his post and has reportedly put the paper up for sale.

But it can’t be unsaid. To read in a mainstream publication that Barack Obama should be killed takes the breath away.

How many other Americans think the same way? Such thoughts didn’t start with Adler. They don’t stop with him.

Now, before some of you strike back with, “Hey, what about those scurrilous attacks on George W. Bush or Ronald Reagan?,” allow me to stipulate that crazed partisans and venomous pundits populate the left as well as the right.

What sets anti-Obama foes apart from the persecutors of Bush, Reagan et al., however, is that the purveyors of this brand of inflammatory rhetoric include the GOP presidential candidates themselves.

Their charges are rude, disrespectful and designed to question Obama’s loyalty to country and commitment to his faith.

John Avlon, CNN contributor and senior political columnist for Newsweek and the Daily Beast, recently chronicled the kind of “radioactive rhetoric” that the presidential hopefuls are spewing to rev up their conservative base. I’ve chosen a few examples of my own.

Newt Gingrich: Obama has a “Kenyan anti-colonial mindset” and is the “most radical president in American history.” Gingrich has also said: “This is an administration which, as long as you are America’s enemy, you’re safe. You know, the only people you’ve got to worry about is if you are an American ally.”

Rick Santorum: Obama has “some phony theology . Not a theology based on the Bible,” and he is “systematically trying to crush the traditional Judeo-Christian values of America.”

Mitt Romney: Obama associates with people who have “fought against religion.” “Sometimes,” Romney said recently, “I think we have a president who doesn’t understand America.”

As Avlon observed: “This line was straight out of the ‘Alien in the White House’ playbook, a riff that reinforced the worst impulses of some in the audience.”

In this political environment, there is no invective too repugnant, too vicious to throw at this president of the United States.

It is in this climate that we celebrate African American History Month and the achievement of generations against all odds. The demonizing and denigration of the nation’s first black president cast a pall over what should be a time of tribute to indomitable Americans.

But we soldier on.

African American History Month concludes next week, and George Washington University will host an event Tuesday “celebrating the African American legacy in Foggy Bottom.”

Since the discussion will be devoted to my old turf, I expect to be on hand. “Half the fun of remembering is the rearranging,” as an Internet posting put it, and this trip down the avenues of yesterday should be worth taking, even if it returns us to things that were hard to bear at the time.

It is the present, and what lies ahead, that is unsettling.

How will observers of African American History Month many years down the road regard the time in which we now live?

Ah, but these things are being said about Obama, we are told, because of his policies, not because of the color of his skin.

It’s never about race; it’s all about the defense of great traditions and storied principles . . . as in cases of the Civil War, Plessy, Brown, lunch counters, bus travel, the poll tax, Jackie Robinson.

It’s sad, and infuriating.

kingc@washpost.com