In The Republican Party’s uphill path to 270 electoral votes in 2016, Dan Balz writes:
Over the past three decades, the political leanings of many states have shifted dramatically. What once was a sizable Republican advantage in the electoral college has become a decided Democratic advantage.
In short, many states that leaned Republican have started leaning Democratic thanks to changing demographics of voters:
Over the past six elections, Republicans have averaged just 211 electoral votes and have not won more than 286 since 1988. Democrats averaged 327 electoral votes for those six elections, and their lowest total, even in losing, was 251 in 2004. Given the current alignment, the Republicans must find states that have been voting Democratic and convert them to their column in 2016.
Meanwhile, in The Democratic Party’s uphill path to 270 electoral votes in 2016, John Sides writes:
What I’d tell strategists looking at state demographics and Electoral College math is this: In 2016, states will swing — almost in uniform fashion — depending on the underlying political and economic fundamentals. Battleground state demographic trends don’t insulate the Democratic Party from (potentially) a relatively unpopular president and (potentially) an economy that is growing but not very fast. Even analysts who believe these demographic trends portend a long-lasting Democratic majority would agree with that, I think.