Newt Gingrich scoffs at the notion that Iran’s leaders might set aside rigid ideology in order to save their own skin. Speaking during last Wednesday’s 20th and perhaps last Republican presidential primary debate for 2012, Gingrich said he “cannot imagine” why Joint Chiefs Chairman Gen. Martin Dempsey told CNN last Sunday that “the Iranian regime is a rational actor.”

Never mind that immediately after 9/11 Iran lent a hand to the United States in its mission in Afghanistan; the assistance came not because Iran loves the United States, but because it liked the Taliban’s destabilizing presence on its border even less.

In a perverse sense, Gingrich and his fellow Republicans on the stage last week prefer a portrayal of unwavering allegiance to ideology that puts reason, pragmatism and compromise out of reach. The lines between them and us are made even sharper. The mindset reinforces the myth of political purity, something that has mattered more than anything during this presidential primary season. And all four remaining hopefuls have fallen short in the eyes of the Republican grassroots.

Here are some of the major criticisms raised during this campaign season:

For Gingrich, it’s a 2008 appearance in an ad campaign designed to spur action against global climate change. As part of the ad, Gingrich posed on a loveseat with then-U.S. House Speaker Nancy Pelosi, D-Calif., something Newt now calls “the dumbest single thing I’ve done.”

Mitt Romney’s sin in the eyes of conservatives is passage of a health-care law during his time as Massachusetts’ governor. “Romneycare,” as it is derided in Republican circles, was the model for “Obamacare,” which means Mitt is left to distance himself from an effort that successfully provided health insurance for more of his state’s residents.

For all his talk about reducing the size and scope of government, U.S. Rep. Ron Paul, R-Texas, is on friendly terms with earmarking, the process by which congressmen shovel federal government dollars into specific projects back home. According to the Center for Responsive Politics, in fiscal 2010 Paul was involved in the earmarking of $17 million for projects mostly in Texas.

Rick Santorum, the former U.S. senator from Pennsylvania, took a large share of suffering at the hands of the purity police Wednesday night. In 2001, Santorum supported President George W. Bush’s No Child Left Behind act. This put Santorum in the unusual position of slinking away from his vote for a mostly sincere effort to reform U.S. public schools. Awk-ward.

Romney found fault with Santorum’s 2004 endorsement of the re-election of Arlen Specter, the moderate Republican senator from Pennsylvania. Specter, who was seeking his fifth term and was entrenched in key senatorial committees, stood to do a lot of good for his state, something Santorum couldn’t quite bring himself to say last week.

Instead, Santorum explained, “Politics is a team sport.”

Perhaps politics could be better explained as an exploit of opportunism. Good politicians are skilled at surveying the field and adjusting to the mood of the country and attempting what seems possible.

In 2008, the political winds looked favorable for doing something about climate change, so Gingrich the savvy politician took the opportunity to be a trendsetter in his party.

Over his career, Congressman Paul has carved out dollars for special projects, just as the vast majority of his colleagues have done. Were he not running for president, it’s unlikely most would care, especially a majority of voters who cast ballots in his district. In other words, he got while the getting was good and when no one was looking.

In 2006, Romney, with the help of his Legislature and U.S. Sen. Ted Kennedy, D-Mass., adopted a health-care proposal supported by a prominent conservative think-tank and other Republican politicians (including Gingrich). The time was right for Romney, and had the Obama administration not built its health-care reform around Massachusetts’ model of an individual mandate, then Romney might be running for president touting Romneycare for all.

And lest we leave the impression this is a one-sided affair, remember what Barack Obama said on the presidential campaign trail in 2008. His 2008 version of health-care reform was far more ambitious than what Obamacare became, with its financial windfall for private health insurers and other compromises. (Anybody recall Obama’s public option allowing Americans to buy into Medicare? It died a painful death during congressional negotiations.) The Obama administration had big dreams but in the end settled for something far less.

Likewise, it was easy for candidate Obama to promise to close the prison facility holding suspected terrorists at Guantanamo Bay, Cuba. His followers fed up with the Bush administration’s anti-terrorism policies were hungry for bold steps. The time was right for Obama to make that call. As president, however, he discovered that the time was wrong to follow through, especially for his fellow Democrats who might be subjected to a weak-on-defense campaign from Republicans.

As Santorum might put it, Obama took one for the team and kept Gitmo open.

Bob Davis is editor of The Anniston Star. Contact him at 256-235-3540 or bdavis@annistonstar.com. Follow him on Twitter at: twitter.com/EditorBobDavis.