In one of the stranger stories circulating on eve of the rain-delayed Republican convention, sources in Romneyland have invoked a highly unusual model for their hoped-for adminstration: The 11th president of the United States, James Knox Polk. From the Huffington Post’s Jon Ward:

… when I asked [Matt] Rhoades in July how Romney would govern if elected, and what Romney might do with the budget and entitlement reform plans Ryan had already outlined, Rhoades’ eyes lit up. He gave me a name: James Polk.

… Polk, who served from 1845 to 1849, presided over the expansion of the U.S. into a coast-to-coast nation, annexing Texas and winning the Mexican-American war for territories that also included New Mexico and California. He reduced trade barriers and strengthened the Treasury system.

And he was a one-term president.

… The idea of a one-term presidency became something of a theme in my conversations with Romney advisers in July … Multiple senior Romney advisers assured me that they had had conversations with the candidate in which he conveyed a depth of conviction about the need to try to enact something like Ryan’s controversial budget and entitlement reforms. Romney, they said, was willing to count the cost politically in order to achieve it.
This is a weird analogy for two reasons. First, Polk isn’t actually an example of a president who sacrificed the hope of a second term in order to achieve necessary-but-unpopular reforms. His achievements were certainly significant – his was probably the most consequential one-term presidency in American history – but they were hardly unpopular; indeed, the Whig opposition had to execute a hasty volte-face after the U.S. victory in the Mexican War, voting overwhelmingly for the Treaty of Guadalupe Hidalgo and nominating a war hero, Zachary Taylor, in 1848 after opposing the conflict at its inception. Polk’s original one-term pledge reflected his position as a compromise candidate in the election of 1844, but had he gone back on that promise and had his health permitted (he died three months after leaving office) he might have been able to win re-election; indeed, he’s a fascinating figure precisely because seems to have chosen retirement less out of necessity than out of a genuine belief that his service to the republic was complete. (I am fairly confident that if a President Romney achieves the present-day equivalent of winning the Mexican War, he won’t be bowing out in favor of Paul Ryan or Marco Rubio in 2016.)

Second, Polk’s major achievements were for the most part irreversible: He had won a war and negotiated a peace, and neither the Whigs nor his fellow Democrats were likely to seek a return to the status quo ante on those questions. Zachary Taylor wasn’t about to give the American Southwest back to Mexico, or tear up the Oregon Treaty and make war with Britain along the Columbia. Whereas the biggest things Romney could possibly do on entitlements and deficits – a premium-support reform of Medicare, perhaps joined to some kind of Social Security overhaul as well – would presumably be phased in very gradually, and thus would be intensely vulnerable to repeal, either swiftly or incrementally, if they proved unpopular enough to cost him re-election. (Much the same goes, albeit on a lesser scale, for any cuts he might make to discretionary spending, changes to the tax code and regulatory policy, and so on.)

This is something that should be particularly obvious given the peril that President Obama’s signature legislative achievement faces if he is defeated this November. I tend to think that repealing the Democratic health care bill outright will be harder than many Republicans believe, but it’s still obvious that the current administration’s legislative victories will be entrenched if Obama is re-elected, and seriously endangered if he is not. And keep in mind the Romney-as-Polk analogists are envisioning making bigger policy changes than Obamacare and phasing them in over a longer time horizon. If Romney actually wants to make these changes stick, he can’t treat his presidency as some kind of all-in poker hand; he probably needs to get some kind of Democratic buy-in (at least in the Senate), and he almost certainly needs to win re-election.

In general, this is how enduring policy change happens in America: Not in one fell swoop (otherwise Prohibition would still be on the books!), but across a series of campaigns and legislative sessions, which gradually entrench and normalize what was initially perceived as risky and controversial. Here Franklin Delano Roosevelt rather than Polk is the model. He didn’t just pass the New Deal: He made sure to get himself re-elected as many times as possible afterward.