Mitt Romney’s response to the attacks on US diplomatic sites in Egypt and Libya—which left a US ambassador and other diplomats dead—was one of the more ignorant and irresponsible statements ever issued by a major party presidential nominee in such a circumstance. Early Wednesday, the Romney camp released a statement that read: “It’s disgraceful that the Obama Administration’s first response was not to condemn attacks on our diplomatic missions, but to sympathize with those who waged the attacks.”

In fact, the Obama administration’s response had been fully in keeping with what the response of a Reagan, Bush, Clinton or Bush administration would have been. “Some have sought to justify this vicious behavior [at the diplomatic sites] as a response to inflammatory material posted on the Internet. The United States deplores any intentional effort to denigrate the religious beliefs of others,” declared Secretary of State Hillary Clinton as the details of the violence in Benghazi were revealed. “But let me be clear: There is never any justification for violent acts of this kind.”

As more information about the killing of US Ambassador Christopher Stevens and the others in Libya became available, Clinton said, “This is an attack that should shock the conscience of people of all faiths around the world.”

While embattled US Embassy officials in Cairo had put out a statement (apparently before the killings in Libya) that said “we condemn efforts to offend believers of all religions,” there was no expression of sympathy with violence. President Obama said in his statement: “I strongly condemn the outrageous attack on our diplomatic facility in Benghazi, which took the lives of four Americans, including Ambassador Chris Stevens. Right now, the American people have the families of those we lost in our thoughts and prayers. They exemplified America’s commitment to freedom, justice, and partnership with nations and people around the globe, and stand in stark contrast to those who callously took their lives.”

Yet, even after the administration response in general and Obama’s own response had been made clear to all, Republican National Committee chairman Reince Priebus continued to feature a Tweet on his official Twitter account that read: “Obama sympathizes with attackers in Egypt. Sad and pathetic.”

Priebus made no effort to apologize, no effort to clarify, no show of even the most minimal sense of duty or responsibility. Political campaigns frequently go to extremes. People say and do things that are inappropriate. But what Priebus has done crosses whatever line of political propriety still exists. He is intentionally creating a false impression with regard to the response of the president of the United States to a violent international incident that could have long-term repercussions.

This is typical of Priebus, who, since he waded into politics as a failed Wisconsin state Senate candidate, has known no bounds in his rhetorical assaults on his political foes. Just two weeks ago, at the Republican National Convention in Tampa, the party chair played on the crudest claims about the president’s Americanism, suggesting that, “Barack Obama has a problem with the American Dream.”

Priebus’s penchant for suggesting that those who disagree with him are somehow un-American is well established. He got called out by MSNBC host Chris Matthews during a Tampa appearance on Morning Joe after he said: “I think Obama’s policies have created a sense that, for whatever reason, he’s looking [for] guidance as far as health care is concerned, as far as our spending is concerned, as far as these stimulus packages are concerned, that he’s looking to Europe for guidance.”

Just last week, when Congresswoman Tammy Baldwin, a Wisconsinite Priebus knows, appeared at the Democratic National Convention, the RNC chair displayed no home state pride. Rather, he claimed that Baldwin, a Senate candidate who would be the first out member of the LGBT community elected to the US Senate if she wins her November race in Wisconsin, advocated policies that “aren’t in line w/ Americans.”

When he isn’t questioning the Americanism of an African-American president or a female Senate candidate, Priebus has been stretching the truth to the breaking point in other ways. During the Democratic National Convention, on the day when President Obama switched his acceptance speech from an outdoor venue to the convention hall because of a severe weather forecast, Priebus announced that: “I hear from our team in Charlotte that it’s a beautiful day in NC—hardly a cloud in the sky!” In truth, torrential rains were sweeping across Charlotte.

After his clash with Matthews, the chairman called the commentator “the biggest jerk in the room.” Democrats may be inclined to suggest that Priebus is the actual owner of the title. But that is just a variation on the political pettiness that is the RNC chair’s modus operandi.

And it missed the point of Priebus’s latest transgression.

When the chairman of a major American party flagrantly and unapologetically lies about the intentions and actions of the president of the United States in a moment of international tension, he plays a politics that damages his own party as much as it does old notions of foreign-policy consensus and bipartisanship.

It is not Democrats who should be calling out Reince Priebus. It is Republicans.

The Republican Party has a rich history of responding honorably and well to dangerous turns of events and immediate challenges facing the United States. This is the party of Michigan Senator Arthur Vandenberg, a fierce critic of the New Deal who became an essential ally of the Roosevelt administration at critical stages during World War II and when the United Nations was called into being. This is the party of Wendell Willkie, the Republican nominee against Roosevelt in 1940 who almost immediately after his election defeat because Roosevelt’s roving ambassador to the world. This is the party of Dwight Eisenhower and Gerald Ford and George Herbert Walker Bush, presidents who frequently recognized the need to work across lines of partisanship and ideology.

Republican National Committee chairs have always been partisans, as have Democratic National Committee chairs. But does anyone seriously imagine that Pennsylvania Senator Hugh Scott, Maryland Congressman Rogers Morton, George H. W. Bush or the tart-tongued Bob Dole would—even in the heat of a campaign—engage in deliberate deception regarding the response of the president of the United States to the killing of US diplomats?

Reince Priebus has dishonored his party.

Honorable Republicans should call him on it.

For more on the GOP response to the attacks in Libya, read Robert Dreyfuss on why Romney’s remarks ought to disqualify him from the Oval Office.