Do front-runners get to speak more in debates?

Republican presidential candidates will enjoy one of two final chances Thursday evening to dominate a debate before the Iowa caucuses open Feb. 1.

As the previous five debates have demonstrated, candidates who speak up the most during a debate can move the needle in their favor. While there are countless factors that determine whether a contender moves up or down in the polls, a set of strong debate performances can provide the springboard a candidate needs to jump ahead in a crowded primary field.