Percentage of U.S. voting population that is white likely to hit all-time low today

Washington (CNN) Barack Obama was catapulted into office eight years ago by what was, at the time, the most diverse electorate in history. The Americans who head to the polls to cast ballots for his successor are even more diverse.

Thirty-one percent of eligible voters will be racial or ethnic minorities, up from 29% in 2012, according to the Pew Research Center. And the share of non-Hispanic white voters eligible to vote will be the lowest in history, the continuation of a steady decline in white voters over the past three decades.

It's a stark reminder of the shifting demographics of the country: The Census Bureau projects that no one racial group will be a majority of the country by the year 2044. Republicans and Democrats looking to chart an electoral future as the country continues to grow browner and younger will have to take heed of these shifts.

The Republican presidential nominee has carried white voters in every presidential election since 1968 by shifting margins.

In the 1980 presidential election, white voters made up 88% of the electorate. That year, Ronald Reagan won 56% of non-Hispanic whites and captured the presidential election in a landslide. Four years later, against Walter Mondale, Reagan won them by 30 points, 66% to 34%. Since Reagan's time though, the white share of the electorate has declined by a few percentage points each presidential year.

Fast forward to 2012. Mitt Romney won a slightly larger share of non-Hispanic white voters --59%-- than Reagan did in his first term -- but lost the presidential race. Why? The share of the white vote was smaller -- 72% -- and Obama crushed Romney with non-white voters.

Most estimates suggest the white vote this year will be around 69%, an all-time low and a three percentage point decline in four years. That difference is more pronounced in a number of states that both candidates are targeting, including Pennsylvania, Ohio, Florida and North Carolina. All have eligible voting populations that are slightly less white than four years ago.