By Sofia Menchu
GUATEMALA CITY (Reuters) - Guatemala's presidential race has tightened in the final stretch with opposition candidate Manuel Baldizon's lead under pressure from an independent as corruption scandals batter the political establishment, opinion polls showed on Thursday.
Baldizon, runner-up in the 2011 vote, is being chased hard by independent contender Jimmy Morales, a television presenter who has benefited from public anger over corruption allegations that have shaken the government.
A survey by polling firm Borge y Asociados for magazine Contrapoder showed the 45-year-old Baldizon backed by 30.9 percent of voters and Morales with 20.6 percent.
Respondents were polled between Aug. 7 and 13, and the poll had a margin of error of 2.8 percent, it said.
Both men are well behind the 50 percent threshold needed to win outright in a first round of voting on Sept. 6. A second-round run-off, if required, is scheduled for Oct. 25.
A previous survey by Borge y Asociados had put Baldizon at 35 percent support, with Morales trailing at 14.5 percent.
A separate survey by Felipe Noguera Consultores conducted Aug. 8-16 gave Baldizon, head of the center-right Renewed Democratic Liberty Party (Lider), 26.1 percent, just ahead of Morales who had 23.2 percent.
The margin of error in the second poll was 2.6 percent.
Guatemala's conservative president Otto Perez has purged his cabinet of several ministers in the last three months following allegations of bribery and other acts of corruption.
The anti-corruption investigations have been driven by a U.N.-backed anti-graft body known as the CICIG, and its findings have also embroiled senior officials inside Baldizon's Lider.
Public discontent over the scandals has played into the hands of Morales, 46, who has pledged to root out graft.
"Showing zero tolerance to corruption will allow us to cleanse our institutions and to restore confidence in them," Morales told Reuters on Thursday.
Under pressure to clear up the corruption scandals, Perez narrowly avoided losing his presidential immunity from prosecution last week as more than half of the Guatemalan Congress voted to strip him of it. [ID:nL1N10O2SC]
Running third in recent polls is leftist and former first lady Sandra Torres. The candidate of Perez's Patriot Party is way behind the leading contenders, polls show.
(Writing by Dave Graham; Editing by Ken Wills)