While Glas denies any wrongdoing, the scandal has given the opposition something to build their negative campaigns on.

Moreno seemed to address the issue in a recent speech during the campaign, saying: "You know you can trust me, I have never let you down and I never will. Let's continue to move forward together. You give me your vote, and I'll give you my actions and my heart."

Correa hopes the government's track record on fighting poverty, building infrastructure and increasing opportunities will be enough to win voters at the polls.

"We went from being the country of impossibilities to being the country of great achievements in all sectors; you know it, we have seen it," Correa said in January during celebrations marking his 10 years in office.

Fernando Casado, an academic and political analyst with the Institute for National Higher Studies, agreed with Paz y Mino that the race comes down to a contest between two different economic and political systems.

He also feels the outcome will be significant for Latin America, where recent elections and political events in countries such as Argentina and Brazil changed the political tide, replacing left-leaning leaders with conservative pro-business presidents.

If PAIS loses, it will mark the "end of an era" for the region's progressive governments; but if it wins, the progressive movements will be maintained, Casado said.