President Obama, as we've written before, is one of the most polarizing presidents in history -- a title for which his biggest competition is his predecessor, George W. Bush.

What that polarization also means, though, is that Obama has been consistently popular (or unpopular). In fact, Obama's approval rating has varied less than any president since at least Eisenhower, according to Pew data.

Obama's highest approval rating is the lowest of any president on the chart above, and his lowest approval rating is higher than anybody in the past half-century. The only president who comes close to Obama in the consistency department is John F. Kennedy, who was president for less than three years.

One main reason for this consistency: Obama's base is bolstered by the unified and largely unwavering support of two large chunks of Americans: liberals and African Americans. In other words, barring some kind of crisis in the closing days of his presidency, it's unlikely his approval rating would slip much below its previous low of 41 percent.