Given the dramatic and historic nature of the agreement between the United States and Iran, it's perhaps no surprise that the criticism has been similarly dramatic. The deal, multiple critics suggest — including in the Wall Street Journal on Tuesday, is worse than the appeasement of Hitler in 1938. We have here the geopolitical corollary to Godwin's Law: the more significant an international agreement, the more likely it is that a participant will be compared to British prime minister Neville Chamberlain.

The Iran deal is tricky for President Obama and the Democrats. CNN's slow trickle release of a poll from last week showed on Tuesday that the party has lost its lead on the generic congressional ballot. This is fallout from Obamacare, not a response to the Iran deal — but even a successful deal on Iran likely wouldn't have changed that trend. Americans, as Democratic strategist Doug Sosnik argues in Politico, are less inclined to see foreign policy as an important focus of the federal government. Meaning that even in the best case, the Iran deal wasn't likely to change Obama's political fortunes.

Being compared to one of history's most notorious failures won't help. By now, Chamberlain's name is synonymous with diplomatic capitulation, bearing the blame for a deal made in Munich in which Nazi Germany was permitted to annex portions of Czechoslovakia, in the hopes that it would slow the country's aggression. Obviously, that didn't work. Conservative commentators were very quick to compare that to the deal brokered by Secretary of State John Kerry and his peers with Iran. Here's the Journal's Bret Stephens falling victim to (what we'll call) Chamberlain's law: the Iran deal is worse than Munich.

Britain and France came to Munich as military weaklings. The U.S. and its allies face Iran from a position of overwhelming strength. Britain and France won time to rearm. The U.S. and its allies have given Iran more time to stockpile uranium and develop its nuclear infrastructure. Britain and France had overwhelming domestic constituencies in favor of any deal that would avoid war. The Obama administration is defying broad bipartisan majorities in both houses of Congress for the sake of a deal.

That argument is more developed than the one made by Charles Krauthammer on Fox News and that in the Washington Times. Obama betrayed a small country (in Stephens' formulation), Israel, that relies on "Western security guarantees." And, Stephens argues — based on nothing in the Iran example — that "each deal was a prelude to worse."

Stephens' formulation of the Munich agreement is pretty generous, perhaps not a surprise given the rhetorical purpose to which he's applying it. By the time of the agreement in Munich, Germany had already invaded and assumed control of Austria. The appeasement of Hitler did offer the British and French a brief window in which to bolster their forces, but the attempt to placate Germany's expansionism was far more obviously too optimistic. Germany's hostility to its neighbors was in a much, much different place than is Iran's. The argument that this deal is a "prelude to worse" is, obvious, simply a prediction, based on the idea that the deal will allow Iran to continue enrichment of uranium. Which, of course, the country was doing anyway — ostensibly for energy generation but, most believe, with the aim of building a nuclear weapon. Chamberlain's concern was that Germany, if not placated, would invade Czechoslovakia. Munich aimed to prevent an eventuality. The deal with Iran seeks to slow activity already in progress.

The concern of Stephens and other conservatives centers on the tension between Israel and Iran, of course. Israel's prime minister has strongly condemned the agreement, increasing an already tense relationship between the White House and Israel. Iran's long-standing hostility to the state of Israel can't be denied, so its rapid and robust embrace of the measure doesn't help those concerned about a deal.

It is worth remembering, though, that the Munich-Chamberlain example could not only have been predicted — it predates even Obama's presidency. In 2008, President Bush suggested (obliquely) that Obama's stated willingness to negotiate with Iran in order to curtail their nuclear weapon development was "appeasement." Sen. John McCain, Obama's opponent for the presidency that year, agreed, mentioning Chamberlain by name.

Asked if he thought Mr. Obama was an appeaser, Mr. McCain sidestepped the question and said: “I think that Barack Obama needs to explain why he wants to sit down and talk with a man who is the head of a government that is a state sponsor of terrorism, that is responsible for the killing of brave young Americans, that wants to wipe Israel off the map, who denies the Holocaust. That’s what I think Senator Obama ought to explain to the American people.”

The head of the government to whom McCain refers, Mahmoud Ahmadinejad, was replaced in August by the apparently more temperate Hassan Rouhani. McCain's response to the current deal, it's worth noting, has been cautious, but open. Chamberlain comparisons are good for pundits and the campaign trail. When it comes to actually trying to prevent war, even hawks like McCain are willing to give negotiation the benefit of the doubt.

The potential benefits of Iran deal obviously far outweigh the immediate political needs of the president. But he certainly hoped that it might serve as the sort of boost he saw following the bin Laden raid. It won't.