There has been much discussion since the inception of the so-called “Tea Party” movement of the fact that it is overwhelmingly white and, to the view of its critics, racist in its messaging.

In articles and radio and television interviews, I have tended to argue against simplistic characterizations of those who attend tea party events and advance its populist message. Indeed, when I attended several of last year’s Tea Party rallies — including a big one on the grounds of the state Capitol in Madison, Wisconsin, where Republican rising-star Paul Ryan spoke — I found common ground with many present on issues like blocking bank bailouts, auditing the Federal Reserve, and defending civil liberties.

But those of us who want to respect this movement as a legitimate expression of libertarian and conservative sentiment weren’t given much encouragement by the tea partisans who showed up in Washington over the weekend to oppose the anticipated passage on Sunday of landmark health care reform legislation.

The ugliest incident came Saturday afternoon.

Congressman John Lewis, the civil rights movement veteran, was across from the U.S. Capitol, not far from where he and the Rev. Martin Luther King Jr. delivered speeches to the 1963 March on Washington for Jobs and Freedom, when he heard a word from his and his country’s past. A crowd shouting Tea Party slogans and waving signs confronted the congressman and spewed crude racist epithets at a man who risked his life to make real the founding promise that all Americans are created equal.

Lewis was leaving the Cannon Office Building when the anti-reform demonstrators descended on him, shouting obscenities and screaming, “Kill the bill, kill the bill.”

Lewis responded, “I’m for the bill, I’m for the bill, I’m voting for the bill.”

Then, according to Lewis and others who were present, the tea party crowd began shouting: “Kill the bill, n—–.”

The incident, which took place barely blocks from where King delivered his “I Have a Dream” speech, was witnessed by other members of Congress and broadly reported by media outlets, including McClatchy Newspapers and Fox News.

Robert Greenwald’s “Brave New Films” project has highlighted some of the most crude behavior (not just racist remarks shouted at African-American members but homophobic remarks aimed at openly-gay Massachusetts Congressman Barney Frank) and launched a campaign to: “Tell the GOP: Apologize for your hate-spewing proxies in the Tea Party Patriots. It is not acceptable for you to build your party’s political fortunes by encouraging and defending bigotry and hatred among your supporters.”

Missouri Congressman Emanuel Cleaver, another member of the Congressional Black Caucus, is seen challenging one of the demonstrators who spit on him.

Cleaver was a few feet away when the protesters began shouting the N-word at Lewis.

“It was a chorus,” said Cleaver. “In a way, I feel sorry for those people who are doing this nasty stuff — they’re being whipped up. I decided I wouldn’t be angry with any of them.”

“It was a lot of downright hate and anger and people being downright mean,” said Lewis, who added that he was distressed that “people are so mean and we can’t engage in a civil dialogue and debate.”

Of the crude language that he heard Saturday, the man whose skull was fractured when he was attacked during a 1965 civil rights march in Alabama said, “I haven’t heard anything like this in 40, 45 years. Since the march to Selma, really.”

The No. 3 Democrat in the House, South Carolina Congressman James Clyburn, another veteran of the civil rights movement, echoed the sentiment with regard to the racist language of the tea party activists.

“It was absolutely shocking to me,” Clyburn told reporters. “Last Monday, this past Monday, I stayed home to meet on the campus of Claflin University, where 50 years ago as of last Monday … I led the first demonstrations in South Carolina, the sit-ins. … And quite frankly I heard some things today I have not heard since that day. I heard people saying things that I have not heard since March 15, 1960, when I was marching to try and get off the back of the bus.”

It is not the case that all Tea Party activists are racists. But Saturday’s incident confirmed that some are. And that left many on Capitol Hill shaken.

Clyburn added that he thought the true character of the anti-reform campaigners was being exposed. “I think a lot of those people today demonstrated that this is not about health care,” he explained. “It is about trying to extend a basic fundamental right to people who are less powerful.”

For his part, Lewis offered the best response when, referring to the “mob mentality” of Saturday’s Tea Party crowd, he said: “The Republican leadership is making a mistake not doing more to disassociate from this.”

Minority Leader John Boehner, R-Ohio, whose own rhetoric has been plenty overheated, did offer the classic “I’m sorry if you were offended…” defense, telling the Fox News amen corner that: “There are a lot of angry Americans and they’re angry over this health-care bill.” Only later did the Boehner allow as how “violence and threats are unacceptable. It is not the American way.” (Perhaps he was offering a gentle reminder to Sarah Palin, who after the vote messaged her followers that it was time to “RELOAD” and posted a SarahPAC Facebook page featuring a map with 20 gun sights targeting incumbent Democrats for defeat. The sights targeted on Democrats who are retiring are colored blood red.)

There’s no question that the Republicans will be done harm if they do not make a clear break with the racist and homophobic excesses of the Tea Partisans.

But it seems to me that the honest players within the Tea Partisans — and there are a good number of them — ought to be more concerned than the politicians in both parties that this movement has challenged.

Tea Party activists need to disassociate from the behaviors that were on display Saturday. Those behaviors discredit sincere activism and insult not just John Lewis but the memory of Ronald Reagan, who wisely declared 20 years after the March on Washington: “(The) long struggle of minority citizens for equal rights, once a source of disunity and civil war, is now a point of pride for all Americans. We must never go back. There is no room for racism, anti-Semitism, or other forms of ethnic and racial hatred in this country.”