Republicans supposedly revere the Constitution, but in its birthplace, Pennsylvania, they are contemplating a subversion of the Framers’ institutional architecture. Their ploy — partisanship masquerading as altruism about making presidential elections more “democratic” — will weaken resistance to an even worse change being suggested.

Pennsylvania’s Republican-controlled Legislature may pass, and the Republican governor promises to sign, legislation ending the state’s practice — shared by 47 other states — of allocating all of its electoral votes to the candidate who wins the statewide popular vote.

Pennsylvania would join Maine and Nebraska in allocating one vote to the winner in each congressional district, with the two remaining votes going to the statewide popular vote winner.

The 2012 Republican candidate might lose the statewide vote but carry, say, nine of the 18 congressional districts, cutting Barack Obama’s yield to 11 electoral votes. But if the Republican candidate carries nine of Pennsylvania’s 18 districts, and the statewide vote — Obama’s Pennsylvania poll numbers are poor — Republicans will have cost themselves nine electoral votes, which would be condign punishment.

Incongruous political cultures coexist in many states, so the temptation to which Pennsylvania Republicans may succumb could become contagious.

Many big blue states (e.g., New York, Illinois, California) have many red enclaves: Democrats, particularly minorities and government employees, are disproportionately concentrated in urban areas. And many reliably red states (e.g. Texas, Georgia) have solidly blue congressional districts.

In 1960, when Richard Nixon lost the popular vote to John Kennedy by 0.2 percent and the electoral vote 303-219, he won 227 districts and 26 states, so under Pennsylvania’s plan he would have won the presidency with 279 electoral votes.

In 1976, Gerald Ford carried 215 districts and 27 states, Jimmy Carter carried 221 districts and 23 states and Washington, D.C. Under Pennsylvania’s plan (and assuming no “faithless” electors), there would have been a 269-269 electoral vote tie and the House of Representatives would have picked the winner.

Pennsylvania’s plan would encourage third parties to cherry-pick particular districts, periodically producing “winners” of electoral votes, leaving the House to pick presidents. The existing system handicaps third parties: In 1992, Ross Perot won 18.9 percent of the popular vote but no electoral votes.

Pennsylvania’s proposal would raise the stakes of gerrymandering. And a swing state such as Colorado would often be neglected: Its nine electoral votes are a pot worth competing for, but under Pennsylvania’s plan, the split might usually be 5-4 or 6-3.

Winner-take-all allocation of states’ electoral votes enhances presidential legitimacy by magnifying narrow popular vote margins. In 1960, John Kennedy won 49.7 percent of the popular vote but 56.4 percent of the electoral vote (303-219). In 2008, Barack Obama won just 52.9 percent of the popular vote but 67.8 percent of the electoral vote (365-173).

Now eight states and the District of Columbia, with a combined 132 electoral votes, are pursuing an even worse idea than Pennsylvania’s. They have agreed to a compact requiring their electoral votes to be cast for the national popular vote winner, even if he loses their popular vote contests. This compact would come into effect when the states agreeing to it have a combined 270 votes.

Deep-blue California supports the compact. But if it had existed in 2004, the state’s electoral votes would have gone to George Bush even though 1.2 million more Californians favored John Kerry.

Supporters of the compact say they favor direct popular election of presidents. But that exists — within each state. The Framers, not being simple, did not subordinate all values to simple majority rule.

The electoral vote system shapes the character of presidential majorities, making it unlikely they will be geographically or ideologically narrow. The Framers wanted rule by certain kinds of majorities — ones suited to moderate, consensual governance of a heterogeneous, continental nation with myriad regional and other diversities.

Such majorities do not materialize spontaneously. They are built by a two-party system’s candidates who are compelled to cater to entire states and to create coalitions of states.

Today’s electoral vote system provides incentives for parties to alter the attributes that make them uncompetitive in important states. It shapes the nation’s regime and hence the national character.

The Electoral College today functions differently than the Founders envisioned — they did not anticipate political parties — but it does buttress the values encouraged by the federalism the Framers favored, which Pennsylvanians, and others, should respect.

George Will is a columnist for The Washington Post. He can be contacted at:

georgewill@washpost.com