If the recent exchanges between President Bush, Barack Obama and John McCain on Hamas and terrorism are a preview of the general election, we are in for an ugly six months. Despite his reputation in the media as a charming maverick, McCain has shown that he is also happy to use Nixon-style dirty campaign tactics. By charging recently that Hamas is rooting for an Obama victory, McCain tried to use guilt by association to suggest that Obama is weak on national security and won't stand up to terrorist organizations, or that, as Richard Nixon might have put it, Obama is soft on Israel. President Bush picked up this theme Thursday. Without naming Obama during his speech to Israel's Knesset, Bush suggested that Democrats want to "negotiate with terrorists" while Republicans want to fight. The Obama campaign was right to criticize the president for his remarks and for engaging in partisan politics while overseas. Many presidents have said things abroad that could be construed as violating this unwritten rule of American politics. But it is hard to remember any president abusing the prestige of his office in as crude a way as Bush did Thursday. Charging your opponents with appeasement and likening them to Neville Chamberlain in the Knesset is a brutal blow. It is bad enough that Republicans use the politics of personal destruction here at home, but to deploy that kind of political weapon at an occasion as solemn as an American president addressing the parliament of a friendly government marks a new low. MCCAIN, MEANWHILE, is guilty of hypocrisy. I am a supporter of Hillary Clinton and believe she was right to say, about McCain's statement on Hamas, "I don't think that anybody should take that seriously." Unfortunately, the Republicans know that some people will. That's why they say such things. But given his own position on Hamas, McCain is the last politician who should be attacking Obama. Two years ago, just after Hamas won the Palestinian parliamentary elections, I interviewed McCain for the British network Sky News's "World News Tonight" program. Here is the crucial part of our exchange: I asked: "Do you think that American diplomats should be operating the way they have in the past, working with the Palestinian government if Hamas is now in charge?" McCain answered: "They're the government; sooner or later we are going to have to deal with them, one way or another, and I understand why this administration and previous administrations had such antipathy towards Hamas because of their dedication to violence and the things that they not only espouse but practice, so ... but it's a new reality in the Middle East. I think the lesson is people want security and a decent life and decent future, that they want democracy. Fatah was not giving them that." For some Europeans in Davos, Switzerland, where the interview took place, that's a perfectly reasonable answer. But it is an unusual if not unique response for an American politician from either party. And it is most certainly not how the newly conservative presumptive Republican nominee would reply today. Given that exchange, the new John McCain might say that Hamas should be rooting for the old John McCain to win the presidential election. The old John McCain, it appears, was ready to do business with a Hamas-led government, while both Clinton and Obama have said Hamas must change its policies toward Israel and terrorism before it can have diplomatic relations with the US. Even if McCain had not favored doing business with Hamas two years ago, he had no business smearing Barack Obama. But given his stated position then, it is either the height of hypocrisy or a case of political amnesia for McCain to inject Hamas into the American election. The writer, an adjunct professor at Columbia University's School of International Affairs, was the State Department's chief spokesman during the Clinton administration. This article was published in the Washington Post.