In most states, presidential elections are fairly simple. Whichever candidate garners the most votes wins all of that state's electoral votes. There are two tiny exceptions (Maine and Nebraska), but that's typically how it works. President Obama won a majority of votes in Pennsylvania, so he got all 20 of its electoral votes.
Over the past year, however, a number of Republican lawmakers in blue states have been pushing an alternative system. The states would split their electoral votes between different candidates. As Dave Weigel points out, this was first floated by conservatives in Ohio and Pennsylvania before the 2012 election, only to get shot down. But now the idea's steadily making a comeback. So let's look at some of the different proposals here — as well as what effect they would have had on the 2012 presidential election.
Pennsylvania I: Last year, Republican State Senate Leader Dominic Pileggi proposed a bill that would have allocated electoral votes depending on the number of congressional districts each candidate won. (Nebraska and Maine both do this.) The overall winner of the state then gets two extra electoral votes.
This would have benefited Mitt Romney and the Republicans significantly. Pennsylvania is a blue state — a majority of voters cast ballots for both Obama and House Democrats in 2012. But because Republicans controlled the legislature and drew the district lines, they've managed to gerrymander things so that they now control 13 of 18 congressional districts. (This is a fairly common practice.)
The end result? Under Pileggi's initial plan, Romney would have won 13 electoral votes and Obama would have won seven — even though Obama carried the state. Needless to say, that idea was deeply divisive and ended up getting shelved.
Pennsylvania II: But never fear, Pileggi's back with a new proposal. This time around, he's suggesting that Pennsylvania split its electoral votes based on the split in the popular vote. The popular-vote winner would then get two extra votes. That, Pileggi said, would "much more accurately reflect the will of the voters in our state." Under this plan, in the 2012 election Obama would have received 12 electoral votes from Pennsylvania while Romney would have received 8.
Ohio: After the 2012 election, Secretary of State Jon Husted also suggested while on a panel that divvying up Ohio's electoral votes by congressional district might be one way to reform the process.* Again, because Republicans have employed gerrymandering to give themselves more seats in a blue state, this would likely benefit the GOP presidential candidate. Under Husted's plan, Obama would have won the popular vote in Ohio, but Romney would have garnered 12 of the state's electoral votes, while Obama would have received just six.
Virginia: Ari Berman points to another recent proposal from Virginia State Sen. Charles Carrico Sr. This one goes much further than any of the above plans. Electoral votes get divided by congressional district. On top of that, another two electoral votes would go to the candidate who wins the most districts. So, in 2012, Obama won the popular vote in Virginia. But under Carrico's plan, Romney would have received 9 electoral votes and Obama would have received just 4.
One common argument for these plans is that it gives rural voters a greater voice; Dave Weigel dissects that strange logic here. But there's also an undeniable partisan appeal. As Berman points out, if GOP-controlled legislatures in Florida, Michigan, Ohio, Virginia, Florida, and Pennsylvania had all adopted versions of this vote-splitting plan, then Romney would have won the White House with 270 electoral votes in 2012.
And... an alternative — the National Popular Vote: The proposals above are pretty crass. But if anyone's looking for a more principled way to reform the electoral college, there's always the National Popular Vote to consider. Under this proposal, states would pledge to award all of their electoral votes to whichever candidate won the popular vote nationwide. But the plan wouldn't take effect until enough states (adding up to 270 electoral votes) signed the pledge.
In practice, this proposal would mean that whichever candidate won the most votes nationwide would then become president. The electoral college would effectively render itself null. A huge difference, of course, is that the National Popular Vote is a national-level reform, rather than an ad hoc effort to siphon away electoral votes from a few blue states.
* Update: To clarify, Husted was suggesting this as one possibility for electoral reform, he was not putting any sort of firm proposal forward.