(This June 5 story has been corrected to clarify Rodriguez edged up 1 percentage point, not Anaya, in paragraph 10)

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MEXICO CITY (Reuters) - Leftist candidate Andres Manuel Lopez Obrador extended his double-digit lead less than a month out from the July 1 presidential election, two voter surveys showed on Tuesday.

Lopez Obrador, who has consistently ranked at the top of polls, saw his support rise to 37 percent in a late May survey by firm GEA-ISA from 29 percent in a late April poll by the same group. That now puts him 14 percentage points above his closest rival.

The 64-year old former Mexico City mayor is making his third bid for the presidency. This time he has capitalized on discontent with the ruling party due to corruption scandals, rising violence and sluggish economic growth.

Right-left coalition leader Ricardo Anaya followed in second place, dropping 1 percentage point to take 23 percent of voter support, the poll showed.

The ruling party candidate, former finance minister Jose Antonio Meade, remained in third place, down three percentage points to 17 percent.

Jaime Rodriguez, the only independent candidate, had 3 percent support.

Twenty percent said they were undecided.

GEA-ISA said it conducted face-to-face interviews with 1,070 people between May 25 and 27. The survey had a margin of error of 3 percentage points.

Another survey published on Tuesday by polling firm BGC showed Lopez Obrador extending his lead to 47 percent support, up from 42 percent in May.

Support from Anaya slipped from 33 percent to 29 percent, Meade rose 2 percentage points to 21 percent, and Rodriguez edged up 1 percentage point to 3 percent support.

The most recent major voter poll, published last week by polling firm Parametria, gave Lopez Obrador a 25-percentage-point lead over Anaya.