Updated

Mexico's governing party is trailing badly in the presidential race and it's unveiling an attack ad aimed at front-runner Enrique Pena Nieto, whose slogan is "I know how to deliver."

The television ad by the conservative National Action Party shows a polluted lake and an unfinished bridge among the list of 608 projects that Pena Nieto says he completed during his term as governor of Mexico state for the Institutional Revolutionary Party.

"Pena Nieto is a liar," the ad says.

National Action candidate Josefina Vazquez Mota trails badly in polls after a series of missteps.

Negative ads run in 2006 by President Felipe Calderon, also of the National Action Party, are credited with sinking then front-runner Andres Manuel Lopez Obrador of the leftist party.