Mexico City, Mexico - Mexico has sent a diplomatic note to the US to protest its neighbor's "interventionist" statements concerning a proposed domestic judicial reform, President Andres Manuel Lopez Obrador said Friday.

This came a day after US Ambassador Ken Salazar told reporters the change, which would see judges and magistrates elected by popular vote, "will threaten" a trade relationship that "relies on investors' confidence in Mexico's legal framework."

Mexico is one of the US' largest trading partners. The two have a free trade agreement that also includes Canada.

"The ambassador's statement... represents an unacceptable act of interference, it violates Mexico’s sovereignty and does not reflect the degree of mutual respect that characterizes relations between our governments," said the protest note, which Lopez Obrador read at a press conference.

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Salazar had claimed the proposed change could pose "a major risk to the functioning of Mexico's democracy." It could "make it easier for cartels and other bad actors to take advantage of politically motivated and inexperienced judges," he suggested.

On Friday, the ambassador wrote on X that his concerns had been expressed "in a spirit of collaboration."

Canada's ambassador to Mexico, Graeme Clark, also underlined investor unease during a meeting with the Canadian Chamber of Commerce Thursday.

"My investors are concerned, they want stability, they want a judicial system that works if there are problems," he said.

Mexico's judiciary is independent, with its own mechanisms for appointing judges. In the case of the Supreme Court, lawmakers vote from among candidates proposed by the president.

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The judicial reform proposal will be put before the session of Mexico's ruling party-controlled legislature that begins on September 1.

The reform has the support of Mexico's incoming president, Claudia Sheinbaum, who will take office on October 1.