Rivals narrow gap on Mexico's Pena Nieto in poll MEXICO CITY (Reuters) - Mexican presidential front-runner Enrique Pena Nieto's still-solid lead has narrowed over the past 10 days, with both of his main rivals making up ground ahead of the July 1 election, a poll published on Thursday showed. Pena Nieto of the opposition Institutional Revolutionary Party (PRI) had the support of 42 percent of people surveyed by polling firm BGC for newspaper Excelsior, compared to leftist Andres Manuel Lopez Obrador and ruling party candidate Josefina Vazquez Mota, both at 28 percent. Pena Nieto's support was down 3 percentage points from a previous poll published on May 28, while Lopez Obrador's support rose 1 percentage point and Vazquez Mota, the candidate of President Felipe Calderon's conservative National Action Party (PAN), gained 4 percentage points. Support for Pena Nieto, who has held a solid lead in polls for the past two years, is slipping after a series of protests by university students in Mexico City and elsewhere against him and the PRI, which ruled Mexico for 71 years before losing power in 2000 election. The protests aim to awaken negative memories of the PRI's long rule in Mexico, which was marked by allegations of corruption and authoritarianism. The anti-PRI sentiment is giving a boost to Lopez Obrador, who is backed by a coalition of leftist parties headed by the Party of the Democratic Revolution (PRD). Lopez Obrador narrowly lost the 2006 race to President Felipe Calderon. Vazquez Mota's candidacy has been hampered by voter distress over rising drug violence in Calderon's war against the cartels. More than 55,000 people have died since Calderon deployed the army to the streets to take on drug gangs shortly after taking office in December 2006. The latest survey was conducted between June 1 and June 5 and surveyed 1,200 households with a margin of error of 2.9 percentage points. Reporting By Dave Graham; Editing by Will Dunham