California Governor Jerry Brown has taken a not-so-subtle dig at Texas' decision to deploy National Guard troops to the border, saying he expects it to be a short-lived measure and that "wiser minds will prevail".
Brown is in Mexico for three days of meetings, focusing on migration, trade, investment and environmental co-operation.
At a news conference on Monday (local time) with Mexican Foreign Relations Secretary Jose Antonio Meade, Brown said the immigration overload of thousands of Central American youths at the border should be seen as a humanitarian issue. The US is coping with a dramatic increase in the number of unaccompanied children attempting to cross the border, coming mainly from Honduras, Guatemala and El Salvador.
Meade said he and Brown agree that the use of law-enforcement or military agencies "is never justified in cases where children are concerned" unless they are providing medical or logistical aid.
Texas Governor Rick Perry announced a decision last week to deploy up to 1000 National Guard troops to the Texas-Mexico border over the next month to combat what he said were criminals exploiting a surge of children pouring into the US illegally.
Asked about that, Brown said: "I hesitate to comment on the thinking that goes into the sending of the Texas National Guard to the border. I would suspect that it would be of relatively short duration and that wiser minds will prevail in the next several months."
Brown acknowledged the immigration surge has become politicised, and said: "My goal is to try as much as I can to frame the issue of the children as a humanitarian challenge. That should appeal to people of all political persuasions." California Attorney General Kamala Harris said on Thursday that she was helping secure lawyers to represent minors during immigration hearings.
Meade, meanwhile, said few of the Central American migrants apply for asylum in Mexico because they are trying to join relatives in the United States.
While many migrants - especially those from Honduras and El Salvador - say they are fleeing gang-related violence in their home countries, less than one in 60 of those caught in Mexico in 2013 asked for asylum in Mexico. The numbers for the first six months of 2014 show only a slight uptick, with about one of 50 requesting asylum. Of those applications, about 20 per cent to 25 per cent have been approved in recent years.
"The fundamental goal, in many cases, is (family) reunification. That means the migrant's desire is really not to stay in Mexico," Meade said. "That explains why there are so few (asylum) requests in Mexico."
The governor's office said Brown would meet privately with Pena Nieto to discuss immigration and other topics.
Brown's trade mission is aimed at increasing direct investments in California, promoting university exchanges and forming environmental partnerships to combat climate change.
The trip, organised by the California Chamber of Commerce, includes a delegation of more than 100 people representing sectors of state government, business, economic development, investment and policy. Delegates paid US$5000 (NZ$5850) each for the four-day trip, which is subsidising the cost of Brown's travel.
"We want to increase trade. We want to deal with some issues on the refugees that are coming across the border. And I also want to collaborate with Mexico in pushing an intelligent climate change agenda," Brown said ahead of the journey.
On Tuesday, Brown is to sign an education agreement, then meet with officials including Mexico's energy secretary and the president of the senate. On Wednesday, the governor plans to wrap up his trip by signing a trade agreement with Mexico, which is California's largest export market.
Business participants include Sempra Energy, BP America and other representatives of the energy, tourism and agriculture industries. Representatives of the Natural Resources Defense Council and the Environmental Defense Fund also are attending.