Primaries are unpredictable: Here's who led on this day 4, 8, 12 years ago

The 2016 presidential primary season continues to be predictably unpredictable, with outsiders leading polls and seasoned political veterans lagging behind. Every time Donald Trump says something offensive, it seems like it will finally be the statement that brings him down. But Trump continues to poll like a front-runner nationally, in Iowa and in New Hampshire.

But just because the last several months have mostly held steady doesn't mean we should expect the candidates in the lead today to win caucuses and primaries. Most voters probably still haven't made a final decision on whom they will support. Let's review who led primary polls on Nov. 25, 2011, 2007 and 2003.

2011, Republican national polls: Following the demise of Herman Cain, Newt Gingrich had just taken the lead from Mitt Romney, who was two percentage points behind. Gingrich would hold that lead for the rest of the year. He lost the lead in early January, but would briefly regain it at the end of the month. Gingrich won primaries in South Carolina and his home state of Georgia.

2011, Iowa Republican Caucus: Gingrich also led in polls of Republicans in Iowa on this day in 2011. He held a two-point lead over Herman Cain, whose campaign was collapsing, and a four point lead over Romney. Eventual caucus winner Rick Santorum was still polling under 4 percent. Keep in mind, the caucus was scheduled a month earlier in 2012 than it will be in 2016.