Pennsylvania is currently perhaps the third most important state in presidential elections. Republicans there are considering a plan to turn it into Rhode Island. That would be terrible for Pennsylvanians, and terrible for American democracy — but it would give a massive short-run advantage to national Republicans.

Here’s the story. The electoral college is mandated by the Constitution as the way to determine the winner of presidential elections, but it’s up to each state to decide how to apportion their electoral votes. Traditionally, states have chosen a winner-take-all system, because that maximizes the state’s clout. Indeed, that’s why large and close states such as Pennsylvania, Florida, and Ohio are so important in presidential elections.

But now, as Nick Baumann reports, Republicans who control Pennsylvania government after the 2010 elections are pushing a scheme to apportion electoral votes by Congressional district (as Maine and Nebraska currently do). The effect would be to basically make Pennsylvania a marginal player in the 2012 election. After all, most House districts (including those in the Keystone State) have lopsided partisan majorities, so they wouldn’t be in play, and parties would be unlikely to devote serious resources to try to pick off a couple of electoral votes in the swing districts — and even less unlikely to devote the massive resources it would take to capture the two remaining at-large votes, given that it would be far more efficient to use the money in much smaller states with more (winner-take-all) electoral votes up for grabs.

As far as the effects of this policy, effectively eliminating Democratic-leaning Pennsylvania from the electoral college would be huge — and if Republican legislatures and governors in Michigan and Wisconsin did the same thing in those Democratic-leaning states, it would combine to establish a large Republican bias in the electoral college (compared to a current situation in which there’s basically either no bias or a very small edge for the Democrats).

This is entirely consistent, as Kevin Drum points out, with GOP efforts to use their 2010 landslide to secure future electoral advantages. This does appear to be a real difference between the parties these days. Democrats after 2008 certainly moved aggressively to pass their agenda, but they placed a priority on substantive policy such as health care reform, while doing little about campaign finance reform, or card check, or DC statehood, or any of the other things that could give them a future institutional electoral advantage. It’s not always clear that the GOP strategy, by the way, is wiser; after all, there is probably no clear policy victory in the 2003-2006 era of unified GOP government that was as significant as the Democratic achievements in 2009-2010. It’s also consistent with Republican “Constitutional hardball,” in which they exploit ambiguities or areas in which norms are not fully codified to secure short-term advantages (think massive expansions of the filibuster, or impeaching Bill Clinton).

The result of all this would be that presidential elections lose a great deal of their legitimacy.

It would be entirely possible for a Republican to win the 2012 presidential election despite losing the popular vote by a solid margin and losing states containing a solid majority of electoral votes. Democrats would likely retaliate the next time they had a chance. Close presidential elections would wind up being decided by all sorts of odd chance events, rather than, you know, who wins the most votes. Yes, the current electoral college system does allow split results such as what happened in 2000, but that’s very different: clear, stable rules make it likely that everyone will accept the results.

In short, it’s an absolutely outrageous plan, terrible for democracy and terrible for Pennsylvania. But extremely good for the short-term prospects of Republican presidential candidates.