MEXICO CITY, Oct 8 (Reuters) - Mexican President Andres Manuel Lopez Obrador's desire to placate the United States in a dispute over water has given the beleaguered opposition a flag to rally around as it tries to loosen his grip on the national agenda.

A leftist energy nationalist who has nurtured friendly ties with his American counterpart Donald Trump, Lopez Obrador says he does not want Mexico to become an issue in the United States ahead of November's U.S. presidential election.

He accuses the opposition-run border state of Chihuahua of jeopardizing a 1944 U.S.-Mexico accord, saying its government has schemed with farmers to block access to a dam to hold up delivery of water due to the United States.

That is untrue, says Chihuahua governor Javier Corral, who has reaped political benefits from standing up to Lopez Obrador. Corral argues Lopez Obrador wants to make him assume the political cost of handing over the water, a federal responsibility that farmers hit by drought are resisting.

The dispute is a window into how Lopez Obrador's rivals are using local issues to chip away at his domination of the political landscape, much as the 66-year-old once did during his long road to the presidency, which he captured in 2018.

"Resistance to the president is going to come from the provinces. Right now, there's a spark catching in Chihuahua," said Roy Campos, head of polling firm Consulta Mitofsky. "Almost taking a leaf out of (Lopez Obrador's) book on how to do it."

The dispute has sharpened Corral's national profile, and last week Lopez Obrador took the unusual step of announcing he would publicly shun him on a weekend visit to Chihuahua.

Facing pressure from their own farmers, the U.S. State Department and the Texas state government have pressed Mexico to honor the deal, under which Mexico must still provide over 250 million cubic meters of water by Oct. 24.

Lopez Obrador has suggested achieving it may be hard to meet unless Chihuahua provides more water. Corral denies this, saying Chihuahua is already delivering more than it did in the last 1 1/2 decades, and that the government has plenty of other options.

"There won't be a conflict between Mexico and the United States over fulfilling the accord," Corral said in an interview. "Mexico will be able to comply in good time."

Some 35 million cubic meters of water would come from Chihuahua in the coming days and the remainder could be covered from Mexico's international dams, said Corral, a member of the center-right National Action Party (PAN).

Mexico's Foreign Minister Marcelo Ebrard on Tuesday told the U.S. State Department the deal will be honored.

Lopez Obrador claims Corral has picked a fight over water to score political points ahead of state elections in June 2021. Corral denies this, and nine other opposition governors came out in support of Chihuahua last month.

Chihuahua elects a new governor next year, and if Corral can help the PAN secure the state for another term in defiance of Lopez Obrador, he could become a prime candidate to challenge for the presidency in 2024, said Campos at Mitofsky.

Corral's popularity had been in the doldrums last year. But as he fought the farmers' corner and criticized Lopez Obrador for his response to the coronavirus pandemic, it crept up.

By August, his approval rating was 45%, double what it was a year earlier, according to Mitofsky.

Ironically, Lopez Obrador is no stranger to intervening in water disputes. In March, he engineered a referendum to cancel a billion-dollar U.S.-built brewery in the border city of Mexicali on the grounds it threatened local water supply.

Rebels

A journalist by trade, Corral has a reputation as a rebel within the PAN and has even drawn comparisons to Lopez Obrador, who made his name by staging protests against the government in the 1990s and 2000s.

The 54-year-old has parried Lopez Obrador's broadsides with relish, saying the president is not used to having critics push back. At the same time, he argues that Mexico is sliding towards an increasingly authoritarian, one-man rule.

Both men are trenchant critics of political corruption and Corral praised Lopez Obrador for hiking the minimum wage and adopting social policies to alleviate chronic inequality.

But too much of government is dedicated to distracting from the economy's slide into recession last year and Mexico's coronavirus death toll, the fourth-highest worldwide, he said.

"He's a master of making people forget about the pandemic and the economy," said Corral, pointing to Lopez Obrador's raffling of the presidential jet he inherited, and his bid to have a public vote in 2021 on putting ex-presidents on trial.

Corral, who left open the possibility of a presidential tilt in 2024, would not be facing Lopez Obrador: the law currently restricts incumbents to a single six-year term, and the president has said he will not change that.

Corral said he believed Lopez Obrador - but only so far.

"What I think," he said, "is that he wants to carry on influencing and taking decisions for years after his term ends."