Andres Manuel Lopez Obrador, Leftist Mexican President Candidate, Won't Concede (VIDEO)

Andrés Manuel López Obrador, long the underdog of Mexico's presidential election, has said he won't concede defeat until final votes are tallied in the hotly contested race, according to the Associated Press.

"We need to know all the results," López Obrador was quoted by the LA Times. "We're going to wait for those results before making any final positions. There is no final word yet."

Reuters reports that with 85 percent of votes in, Institutional Revolutionary Party (PRI) candidate Enrique Peña Nieto leads with 38 percent of votes, 5.4 percentage points ahead of López Obrador. The candidate from current President Felipe Calderón's National Action Party (PAN), Josefina Vázquez Mota, garnered 25.4 percent of votes.

Despite López Obrador's refusal to concede, President Calderón has already congratulated Peña Nieto on his victory.

The LA Times notes this year's election reminds many of 2006, when López Obrador also refused to accept defeat, which led to protests that shut down Mexico City.