MEXICO CITY (Reuters) - Mexico's National Electoral Institute (INE) on Sunday confirmed that President Enrique Pena Nieto's ruling party emerged as the strongest force in elections last weekend, which INE forecasts say will enable it to retain control of the lower house.
A preliminary INE estimate seen by Reuters showed that Pena Nieto's Institutional Revolutionary Party (PRI), plus its allies, the Green Party and the smaller New Alliance Party, would be allotted a total of 260 seats in the 500-member lower house of Congress, up from 251 before the midterm vote.
However, electoral authorities will not formally give the seat distribution until late July, when the appeals process has concluded, an INE official said. The institute's preliminary seat estimates are unchanged, the official added.
Keeping the lower house would be a boost for Pena Nieto, who has been under pressure for months over security lapses, political corruption and anemic economic growth.
On Sunday, the INE confirmed that the combined share of the vote captured by the PRI and its allies was some 40 percent, or two percentage points lower than their 2012 result.
But the PRI was helped by fragmentation of the vote and the fact that some parties failed to get 3 percent of the vote, the minimum required to win seats by proportional representation.
Support for the PRI's main rival, the center-right National Action Party (PAN), dipped five points to 21 percent: enough for 108 lower house seats, the internal INE estimate showed.
The main leftist grouping, the Party of the Democratic Revolution (PRD), saw its lower house position cut almost in half to 56 seats in that estimate.
The big winner on the left was two-time presidential runner-up and former Mexico City Mayor Andres Manuel Lopez Obrador, a former PRD stalwart whose new party Morena took nearly 8.5 percent of the vote, projecting a haul of 35 seats.
The PRI and its allies are just short of a majority in the Senate, which was not up for re-election.
Pena Nieto is not expected to rely on Congress as much in his last three years, having fulfilled most of his main legislative pledges, including measures to end the state oil and gas monopoly and open up the telecommunications sector to competition.
But the government still has some major initiatives pending, including an urban reform bill and legislation aimed at encouraging investment in rural areas.
(Reporting by Dave Graham; Editing by Jonathan Oatis)