WASHINGTON Poor Mitt Romney. With every poll showing him in the lead for the Republican presidential nomination, his heart must sink.Like Hillary Clinton, Rudy Giuliani and quite a few others who never got to be US President, Romney has the misfortune of being an early front-runner. Normally, we'd expect the rest of the field to make an issue of every crazy, intemperate thing the leading candidate has ever said or done.This year, however, the pack is assailing Romney with documented examples of chronic, blatant, incorrigible moderation. Even shudder pragmatism.Oh, the humanity.The truth is that Romney is basically an ideological conservative who believes in tax cuts as a panacea and is content to watch the American middle class continue its long, sad decline. But in today's Republican Party, merely positioning oneself to the right of Ronald Reagan isn't enough. Apparently, it's also necessary to eschew all reason.Hence the young campaign's most unfortunate new coinage, courtesy of Tim Pawlenty: “Obamneycare.”That's the word he used Sunday to describe President Obama's healthcare law, which borrowed ideas from the reform package Romney devised and implemented when he was governor of Massachusetts. Obamacare plus Romneycare equals ... OK, we get it, we get it.T-Paw clearly received the stop-making-sense memo and perhaps took it a bit too seriously. Last week he released an economic “plan” I'm stretching the word here meant to showcase his boldness and optimism. Instead, he drew near-universal scepticism, along with quite a bit of laughter.Not to be outflanked on the GOP's biggest issue, Pawlenty proposed tax cuts so deep that the deficit would soar by $5.8 trillion over the next decade. To mitigate this disastrous projection which comes from the Pawlenty campaign itself T-Paw assumes that his chainsaw tax-cutting will somehow induce the economy to grow at a sustained rate of five percent a year.That's more than double the expected rate, and will not happen but even if it did, and pigs learned how to fly, the deficit would still grow by $2 trillion over ten years. Pawlenty acknowledged Sunday that his plan is “a stretch” and perhaps should be described as “aspirational.” You know, like planning to fund one's retirement by buying a lottery ticket.Since Romney could never endorse a proposal so contemptuous of basic arithmetic, I suppose Pawlenty did succeed in defining himself as a kind of anti-Romney. T-Paw's problem is that he's stuck down toward the bottom of the pack along with all the other also-ran anti-Romneys, such as former Sen. Rick Santorum, who charges that Romney isn't a true conservative at all.For good measure, Santorum includes Jon Huntsman, who was Obama's ambassador to China before he quit to ponder a presidential run.“I think they have held positions in the past that have not been conservative, and I think they have to account for those,” he said of Romney and Huntsman. “I think what people are concerned about and what they saw in ... presidents in the past who are Republicans is that they say one thing ... and then when they govern, they don't govern as conservatively as they talk.”That's not quite fair. Romney is a conservative by any reasonable definition of the word. It's just that he has a habit of taking objective reality and the views of his constituents into account.When he was running one of the nation's most liberal states, he governed as if he were pro-choice. When he looked for Republican-endorsed ideas to expand health-insurance coverage, he settled on the universal mandate that lies at the heart of, groan, Obamneycare. When the nation was on the precipice of a new Great Depression in 2009, he supported an economic stimulus package but differed with the one that Obama and the Democrats enacted.Romney believes in science and therefore accepts that human activity is contributing to climate change. He said in 2007 that he supported cap-and-trade energy policy “on a global basis,” but not for the United States alone.He was for comprehensive immigration reform until his campaign four years ago, when he became a hardliner, but now he seems to be trying to edge back toward reality on the issue.I've always believed that Romney's chief asset as a potential GOP nominee is his ideological flexibility. But his chief impediment to winning the nomination is a recidivist pragmatism that causes him to commit deeds that today's GOP will not let go unpunished.Eugene Robinson's e-mail address is –eugenerobinson(at)washpost.com