But if more reliably blue states like Michigan, Pennsylvania, and Wisconsin were to award their electoral votes proportionally, Republicans would be able to eat into what has become a deep Democratic advantage.

All three states have given the Democratic nominee their electoral votes in each of the last six presidential elections. Now, senior Republicans in Washington are overseeing legislation in all three to end the winner-take-all system.

Obama won the trio in 2008, handing him 46 electoral votes. Had electoral votes been awarded by district, Republican nominee Mitt Romney would have cut into that lead. Final election results show that Romney won nine of Michigan's 14 districts, five of eight in Wisconsin, and at least 12 of 18 in Pennsylvania. Allocate the two statewide votes in each state to Obama, and Romney would have emerged from the three Democratic states with 26 electoral votes, compared with just 19 for Obama (and one district where votes are still being counted).

Republicans are able to contemplate such a bold plan because of their electoral success in 2010, when the party won control of state legislative chambers and the governorships in all three states, giving them total control over the levers of state government.

"If you did the calculation, you'd see a massive shift of electoral votes in states that are blue and fully [in] red control," said one senior Republican taking an active role in pushing the proposal. "There's no kind of autopsy and outreach that can grab us those electoral votes that quickly."

The proposals, the senior GOP official said, are likely to come up in each state's legislative session in 2013. Bills have been drafted, and legislators are talking to party bosses to craft strategy. Saul Anuzis, the former chairman of the Michigan Republican Party, has briefed Republican National Committee Chairman Reince Priebus and Chief of Staff Jeff Larson on his state's proposal. The proposal "is not being met with the 'We can't do that' answer. It's being met with 'I've already got a bill started,'" the official said. Republican state legislators are motivated to act after Romney's loss. And the party lost legislative seats in all three states, adding urgency to pass the measures before voters head to the polls in 2014.

Tweaks of electoral-vote rules are hardly unprecedented, according to Michael McDonald, a political scientist at George Mason University. State legislatures routinely changed Electoral College allocation rules in the early years of the republic; the political fallout then can inform present-day lawmakers considering the changes.

"State legislative elections became tantamount to the presidential election in a state. Local issues were put aside for presidential politics," McDonald said. "These states legislators thus risk the nationalization of their state politics, to the detriment of their personal careers. State legislators learned that once they fixed the Electoral College rules, national politics no longer dominated state elections."