Welcome to the GOP's great political experiment In 2005 Mitt Romney decided to run for president, and set about making himself acceptable to the Republican party's conservative base. He reversed his pro-choice stance, abandoned his support for cap and trade, and discovered a set of almost brutally nationalist foreign policies. The journey from centre-right to right-right nearly killed him, but he made it. Announcing his exit from the 2008 race before the Conservative Political Action Committee, he was introduced to wild applause as a "conservative's conservative." Tragically, the party has developed since 2008 in such a way that Mr Romney once again finds himself suspiciously moderate to the base. Part of the problem is his Massachusetts healthcare plan, which President Obama has imported to the national level only for the GOP to discover that it amounts to the greatest threat to freedom in the history of the Republic. More broadly, Mr Romney's difficulty in rousing himself into a state of bug-eyed terror when denouncing the administration has caused the party faithful to serially attach themselves to a procession of retreads who more authentically channel their mental state. He has used his financial advantage to unleash an advertising barrage against these hapless foes. And, incredibly, he has positioned himself to their right, lambasting Newt Gingrich as a climate-change opponent and Rick Santorum as a labour-friendly big spender. All this merely underscores the very strange match between party and nominee. Republicans have been lurching rightward for several decades, a process that slowly redefined died-in-the-wool arch-conservatives of the 1970s such as Bob Dole as squishy moderates of the 1990s. The process has sped up visibly since Mr Obama assumed the presidency. Republicans viewed the election of Mr Obama, powered by younger and browner voters, as a frightening portent of the future. They responded to this shock by setting about to stage a decisive confrontation, taking up a more radical opposition to social spending (on those not currently elderly) than they had in generations. Mr Romney offers a useful measure of this lurch. The rightwing candidate of 2008 is now the leftwing candidate of 2012, without his policies having moved left one iota. Can this possibly work? Possibly, but the answer depends on your perspective. The Republican party seems to be pitting two of the great theories of political science against one another. One of these is median voter theorem, which holds that the party that manages to occupy the ideological ground closest to the centre wins. The second perspective holds that voters pay little attention to candidates" positions and instead vote on material conditions, such as wars and the health of the economy. The Republican party, without attempting to do so, has been engaged since 2009 in a great political science experiment. In the 2006 and 2008 elections the party suffered a decisive repudiation, suggesting that a hard rightward turn would result only in continued drubbings. On the other hand, the Democrats took hold of the cockpit just before the world economy nosedived into a mountain. One theory suggests voters will punish the Republican party for its extremism, and the other implies they will punish Democrats for the economy. And, of course, if the economy continues its apparent momentum into November, both theories imply the GOP will be soundly thrashed. The late economist Herb Stein famously observed that any trend that can't go on forever won't. Accordingly, the GOP's rightward surge will end, hopefully before the party has reconstituted itself as a paramilitary organisation organised primarily in fortified mountain bunkers. The frightening thing is that it's hard to see how this process can end soon. Mr Romney's probable nomination will have the base sputtering in frustration, as it again concludes it was forced to accept a non-believer as their standard-bearer (which is its interpretation both of why George W. Bush ultimately failed and of why John McCain lost to Mr Obama). If Mr Romney now goes on to win the presidency, however diligently he attempts to keep the promises he has made to the right, at some point he will bump up against the systemic limits of the office. Lacking the sort of deep-seated goodwill that made Ronald Reagan's compromises tolerable, conservatives will turn against him, as they turned against the last two Republican presidents. And if Mr Romney loses, he will provide even more fuel to the true believers, and the contest for a more authentic radical will recommence. The writer is a political columnist for New York magazine