With Barack Obama still on his grand tour overseas, John McCain's campaign took a potshot at the presumptive Democratic presidential nominee for supposedly violating an agreed-upon rule of U.S. politics. It did so by sending out an email to reporters highlighting a statement pundit David Gergen uttered on CNN:

Barack Obama made the first mistake of his trip, in my judgment, in releasing a statement in which he said exactly what [Iraqi Prime Minister] Maliki had said in those conversations [with Obama]. We have a long tradition in this country that we only have one president at a time. He's the commander in chief and the negotiator in chief. I cannot remember a campaign which a rival seeking the presidency has been in a position negotiating a war that's under way with another party outside the country.

Gergen, counselor to presidents of both parties, was overstating the case. After all, it was Maliki who had told Der Spiegel days before he chatted with Obama that he fancied Obama's call for a phased withdrawal of U.S. troops from Iraq. Obama was not giving away any big secret by sharing the basics of what he and Maliki had discussed. But Gergen was truly hyping this episode by asserting no presidential contender had ever dared to interfere in wartime policy-making. There was a time when a presidential candidate truly did undermine a president while a war was under way--and Gergen worked for this candidate once he became president: Richard Nixon.

In a 1991 letter to The New York Times, William Bundy, the Assistant Secretary of State for East Asian and Pacific Affairs during the Lyndon Johnson administration, described the "covert operation" mounted during the 1968 presidential candidate by Nixon, the GOP nominee, John Mitchell, his campaign manager, and Anna Chennault, a Republican activist. Bundy noted, as others have, that Chennault became Nixon's secret channel to President Nguyen Van Thieu of South Vietnamese through South Vietnamese Ambassador Bui Diem. (Diem, Mitchell and Chennault met together in Nixon's New York apartment sometime in the summer of 1968). And in the fall of 1968, the Johnson administration learned (via intercepted South Vietnam embassy cables) that Chennault had been conveying "Republican" messages to Thieu, urging him to abort or cripple the peace talks then proceeding between President Johnson and Hanoi. The Nixon camp did not want the Democrats to score a political victory by negotiating a peace agreement right before the election. And the implied or explicit message to Thieu was that Thieu would get a better deal if Nixon were elected president. As Bundy noted, Thieu took actions that impeded the peace talks.

Bundy wrote:

On Nov. 3, two days before the election, Mr. Johnson taxed Mr. Nixon with Mrs. Chennault's activities, and Mr. Nixon categorically denied any connection or knowledge -- almost certainly a lie in light of later disclosures. In the circumstances, Mr. Johnson and Mr. Humphrey decided, separately, not to raise what would surely have been a highly divisive issue so late in a campaign. A year later, Theodore White, describing the episode in his book on the 1968 campaign, rightly called Mr. Humphrey's decision one of the most decent actions ever taken by an American political figure.

What the Nixon crew did was truly unprecedented messing around--actively and secretly undercutting ongoing peace talks to gain political advantage. And Gergen worked in the White House of the fellow whose campaign did this. Before Gergen again claims Obama has broken precedent, he might want to review this ugly episode.