Leftist front-runner Andres Manuel Lopez Obrador of the National Regeneration Movement (MORENA) attends an event organised by Mexican Employers' Confederation (COPARMEX) in Mexico City, Mexico May 17, 2018. REUTERS/Gustavo Graf

MEXICO CITY (Reuters) - Sunday’s second Mexican presidential debate likely did little to blunt leftist front-runner Andres Manuel Lopez Obrador’s momentum ahead of the July 1 election, two post-debate opinion polls suggested.

Lopez Obrador, a former Mexico City mayor who is leading by 20 percentage points in some voter surveys, spent much of the debate using stock phrases and sparring with second-placed challenger Ricardo Anaya, who is leading a right-left coalition.

As they fought, they largely ignored third-placed Jose Antonio Meade, the ruling Institutional Revolutionary Party’s candidate, who was able to focus more on pitching his proposals. Meade is well behind Lopez Obrador in surveys of voting intentions.

A phone survey of 2,000 people by polling firm Massive Caller, published on Sunday after the debate, showed that 35 percent of respondents regarded Anaya as the debate winner, 33 percent went for Lopez Obrador, and 25 percent for Meade.

The debate appeared to do little to change public perceptions of who would eventually triumph in July, though, with 43 percent predicting Lopez Obrador would emerge victorious, compared with 36 percent for Anaya and 16 percent for Meade.

A smaller poll of 284 people by Mexican statistics firm Numerus, published on Tuesday, gave Meade the win - but found just 31 percent of respondents followed the debate.

Pollsters say ad hoc telephone surveys do not necessarily provide a reliable reflection of public opinion.