IN 1984, after serving three terms in the House of Representatives, Ron Paul was defeated by Phil Gramm in Texas’s Republican Senate primary. Paul left Congress, and a few years later he left the Republican Party entirely to run for president on the Libertarian line. In the 1988 election, after a campaign that Texas Monthly compared to something “out of Robert Altman’s movie ‘Nashville,’ ” he took home just 0.47 percent of the popular vote.

Thus marginalized by the public, the former congressman proceeded to marginalize himself. Through the various newsletters that bore his name — most notably the Ron Paul Political Report and the Ron Paul Survival Report — he spent the early 1990s as a peddler of far-right paranoia. In an exhaustive 2008 piece for Reason magazine, Dave Weigel and Julian Sanchez argued that the most abhorrent language in Paul’s eponymous newsletters — the claims that the Rev. Martin Luther King Jr. “seduced under-age girls and boys,” that AIDS sufferers “enjoy the attention and pity,” and so on — weren’t actually written by the man himself. But the fact that they had Paul’s imprimatur suggests that the former congressman had grown comfortable way out on the xenophobic fringe.

That fringe is like the Hotel California: When public figures hang out there for a while, they usually find that it’s easier to check out than to leave. Yet in 1997, Paul was back in Congress, representing the same Republican Party that he’d previously abandoned. In 2008, after a decade as a marginal figure on the Hill, his long-shot campaign for the presidency suddenly gained him one of American politics’ most devoted followings. And now this following has grown large enough that a man whose Survival Report once counseled would-be militia members to “avoid the phone as much as possible” has a chance to win the Iowa caucuses.

There are two commonplace interpretations of Paul’s unusual trajectory. To his many sympathizers — libertarians, dissident conservatives and some left-wingers as well — the extremism in his past has nothing to do with the issues that he’s campaigning on today. The case for Paul, as The Atlantic’s Conor Friedersdorf put it, is that “he alone, among viable candidates, favors reforming certain atrocious policies” — scaling back America’s overseas commitments, ending a failed war on drugs, curbing a runaway public sector and reducing the powers of an imperial presidency. The newsletters may reflect badly on his past, but in the current political landscape he’s a voice of reason rather than of madness.