In key Mexican state, opposition leads in poll for July vote By Miguel Gutierrez MEXICO CITY (Reuters) - Mexico's main opposition conservatives are on track to retain the key electoral bastion of Baja California next month, according to a poll released on Friday, in a vote that could strengthen a fragile cross-party alliance built by President Enrique Pena Nieto to re-energize the economy. Falling short of a majority in Congress when he won office last year, Pena Nieto forged a loose pact with the two major opposition parties to work together on economic reforms. Sparring between the National Action Party (PAN), the opposition leftist Party of the Democratic Revolution (PRD) and Pena Nieto's Institutional Revolutionary Party, or PRI, has threatened to derail his plans to improve the tax take and overhaul state oil giant Pemex. The conservative PAN is seen as his most natural ally, especially on high stakes energy reform. Since its 2000-2012 rule of Mexico ended in December, the PAN has been rocked by infighting, and on July 7 voters will elect a new governor in Baja California, which was the first state to bring PAN to power 24 years ago. To lose it would be a heavy blow for the party. The PAN has held the state continuously since 1989, increasing the risk that voters could opt for a change. However, the voter survey by polling firm Demotecnia showed some 53 percent of the electorate favored the candidate representing the unusual PAN/PRD coalition running in the state, while 45 percent backed the PRI's hopeful. Sharing a border with the United States, Baja California is one of 14 states that will hold local elections next weekend. It is the only governorship up for grabs, and has become a symbol for the PAN since its capture from the PRI. The centrist PRI dominated Mexico in the 20th Century, holding the presidency from 1929-2000, during which it acquired a reputation for corruption, vote-rigging and authoritarianism. Both the PAN and the PRD have pounced upon any hint of electoral fraud by the PRI, and Pena Nieto's reliance on the so-called Pact for Mexico he created with the opposition means his party has to tread carefully in the elections. A change of power in Baja California would increase pressure on national PAN chairman Gustavo Madero, who has faced persistent grumbling from internal party critics that the Pact for Mexico has undermined support for the conservatives. The pact has produced a major education reform as well as a landmark law aimed at curbing the power of Mexican telecoms tycoon Carlos Slim and broadcaster Televisa, though many of the details of those bills must still be thrashed out in Congress. Madero has responded to critics by threatening to quit the pact if the PRI does not play fair, and has repeatedly accused the governing party of abusing its power to gain an advantage in the first major round of elections since last July's presidential vote. If the PAN cries foul following the elections, it is likely to complicate negotiations over the national energy and tax reforms, both of which are due to be presented the Mexican Congress in the next 10 weeks. The survey, conducted between June 25 and 26, consulted 1,000 people and has a margin of error of 3.2 percent. Reporting by Miguel Angel Gutierrez; Writing by Luc Cohen; Editing by David Alire Garcia and Alden Bentley