In a word, no.
The mechanics of the Electoral College are still designed to give a single candidate a mandate, and a necessary result of that is to marginalize third party candidates. An analysis of third party candidates will show why this is so difficult - Simply put, the margin to achieve an electoral vote anywhere is simply still very high.
Let us look at the 2010 allocation of electoral votes. The minimum amount of votes needed to even get 1 electoral vote, outside of CA, TX, FL, and NY, is still pretty high:
- (State / Votes / % needed for 1 electoral vote)
- California 55 2%
- Texas 38 3%
- Florida 29 3%
- New York 29 3%
- Illinois 20 5%
- Pennsylvania 20 5%
- Ohio 18 6%
- Georgia 16 6%
- Michigan 16 6%
- North Carolina 15 7%
- New Jersey 14 7%
- Virginia 13 8%
To put this in perspective, let us look at "the 10 most successful third party candidates ever," according to this link. The top four entries, in my mind, do not apply:
Abraham Lincoln (1860) – 39.8%
Predates the 2 party system
Theodore Roosevelt (1912)
As a former President from a major party, 1912 was really just an intra-party fight that went to the general election.
William Jennings Bryan (1896) – 45.8%
My personal hero, alas, he was the nominee of a major party and of two third parties.
Millard Fillmore (1856)
A former president who also competed before the two party system.
As such we really have:
Ross Perot (1992) – 18.6%
Probably would have earned votes in several states. Assuming equal support in all states, would have only received an electoral vote in states with more than 6 – That’s Utah & up, so, yes, Perot would have gotten several electoral votes, but nowhere near a majority.
Robert LaFollete (1924) – 16.6%
Did win 13 electoral votes from Wisconsin, and yes, if support were more even distributed, could have received votes.
George Wallace (1968) – 13.5%
Did win 46 votes, mostly in the South. That said, his popularity was concentrated, which in the end, over represented his popular vote.
Strom Thurmond (1948) – 2.4%
Did win 39 electoral votes in 4 southern states. Also, w/Harry Byrd in 1960, 14 of 15 votes. Had his support not been so concentrated in the South, however, he wouldn't have gotten any.
Now, we get to the also-rans, and the ones people generally think about:
Ralph Nader (2000) – 2.74%
Assuming equal distribution, could have only gotten 1 electoral vote in California. And that would be it.
Ron Paul (2008) – 0.3%
Would have gotten no electoral votes, even under this system.
Now, arguably, you would have more of an incentive under a proportional system, but the numbers still bear out how exceedingly difficult being a third party candidate is in a Presidential election. The Electoral College ensures that a President is both deeply and widely acceptable. That's the point - and #3 will always find it difficult to do either, let alone both.