I think I can fill in a little bit more than just adding to the liberal chorus of outrage over Bush's comments to the Knesset to the effect that the Democrats, through the practice of diplomacy (disdained in itself by the Bush administration), commit appeasement like Chamberlain's appeasement of Hitler. Three points:
1) The radicals and terrorists reject negotiation, just as Bush does. It is a canard to suggest that Obama thinks that "some argument" will change the minds of radical religious militants. Obama (and Carter) are trying to engage now-marginalized moderate Arab voices, as any sensible diplomacy must. What Bush's rhetoric does is to imply that any representative of, say, Iran or Syria is a "terrorist," something not even the Israelis would claim: thus Bush dangerously distorts grave matters of foriegn policy in the name of holding on to political power.
2) What needs to be repeated enough to get through to the popular consciousness is that the Republicans plan to run a national security campaign against the Democrats. In the 2004 election Vice-President Cheney publicly stated that a Democratic victory would make terrorist attacks more probable. It might be that the Democrats should engage with this issue, rather than trying to change the subject: voters can decide at the polls whether the appropriate approach to reforming America's diplomatic profile in the years to come is engagement or belligerence. There is no doubt that John McCain would continue with the current belligerence.
3) Common sense: if you are a radical anti-American of any kind, and particularly if your goal is to alienate the Arab world from the USA, what you want is for the Republican conservatives to stay in power. It greatly legitimizes Al Qaeda and other such groups when they are portrayed by the Americans as military foes, whereas the European approach, to view them as a problem for law enforcement, both diminishes them and has proved much more effective in terms of both security and diplomacy. I'm sure Osama bin Laden is hoping for a Republican victory, just as Raoul Castro is: that would help to keep them in business.