MEXICO CITY (Reuters) - Mexico's presidential front-runner Enrique Pena Nieto maintained his wide lead over leftist Andres Manuel Lopez Obrador and his Institutional Revolutionary Party (PRI) could win a majority in Congress, a new poll less than a week before the election showed on Tuesday.
The latest voter survey for the July 1 election by Consulta Mitofsky showed support for Pena Nieto at 38.4 percent, up 0.8 percentage points from a poll published last week by the firm.
Most polls show Pena Nieto, a 45-year-old ex-governor from Mexico's most populous state, with a double-digit lead over his rivals.
But the leftist Andres Manuel Lopez Obrador, who narrowly lost the last election in 2006 to President Felipe Calderon, says the surveys are biased against him.
Support for Lopez Obrador had surged in recent weeks after a series of youth-led protests against Pena Nieto and the opposition PRI, which ruled Mexico for seven decades before losing power in a 2000 election.
Lopez Obrador rose 1.1 percentage points from the Mitofsky poll a week ago, to reach 25.4 percent.
Support for Josefina Vazquez Mota, from the ruling National Action Party (PAN), was unchanged from the previous poll at 20.8 percent.
The PAN is struggling as voters tire of a brutal drug war, which has claimed around 55,000 lives during Calderon's administration, and lackluster economic growth. The party is plotting its possible future in the opposition where it could play a key role in Congress.
The poll showed the PRI, in coalition with the small Green Party, winning a working majority in Congress.
Mitofsky said the PRI's alliance could win between 274 and 304 seats in the 500-member lower house of congress and between 66 and 73 spots in the 128-member Senate.
(Reporting by Mica Rosenberg; Editing by Simon Gardner and Philip Barbara)