REPUBLICANS FIND THEIR BRIDGE TO THE 19TH CENTURY…. The Republican majority in the Iowa House this week passed a measure declaring that they intend to ignore a federal law they don’t like. It’s unlikely to pass the state Senate, but it’s a rather striking development anyway.

The underlying issue is called “nullification,” and it was a popular concept with conservatives before the Civil War. The idea has been deemed hopelessly ridiculous by the American mainstream — in both major political parties — for generations, which is why it’s slightly horrifying to see how common it’s become in far-right circles over the last couple of years.

Indeed, just over the past two weeks, in addition to Iowa’s state House stoking the confederate fires, the president of the Arizona state Senate wants to create a committee that could “nullify in its entirety” federal laws state officials disapprove of, while Idaho Gov. Butch Otter (R) announced his support for a law nullifying federal measures he doesn’t like. (Otter’s Republican Attorney General felt compelled to explain, “There is no right to pick and choose which federal laws a State will follow.”)

Nullification isn’t exactly secession from the Union, but it’s fair to characterize it as secession-lite.

In other words, this is simply and plainly stark raving mad. It’s hardly news that contemporary Republicans have become more radical, but this nullification talk helps drive the point home nicely.

Dana Milbank had a good column a while back on those who claim “states can merely ignore any federal law they don’t like.”

[N]ullification, like secession, has been tried before, with poor result. In 1832, Andrew Jackson threatened to use force against South Carolina for nullifying federal law, saying the state was on the brink of treason and argued that “to say that any state may at pleasure secede from the Union is to say that the United States is not a nation.” A compromise held off violence for another quarter century. […]

If a state thinks the law is unconstitutional, it can challenge the law in court, as Virginia is doing. If people don’t like the law, they can elect a new Congress and president to repeal it. Or, they can attempt to amend the Constitution, as several Republican lawmakers would do with the proposed repeal of the 14th Amendment, the one with all that nonsense about equal protection under the law. But secession and nullification have all the legitimacy of a temper tantrum.

And yet, that tantrum is nevertheless becoming increasingly common, as we’re seeing this week.

There is no better example of hysterical Republican extremism. Such madness would have been laughed at by the GOP mainstream not too long ago, but is now a familiar component of the party’s message of the 21st century.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.