A top adviser to US President Donald Trump said that the president's emergency declaration could allow "hundreds of miles" of barriers to be built on the Mexican border before the 2020 election.
"You're looking at hundreds of miles," Stephen Miller said on "Fox News Sunday," "probably a couple hundred miles" by September 2020, two months before the election.
Trump has made clear he plans to exploit the issue in his re-election campaign, even amid sharp criticism from Democrats, rights groups, border-state landowners - and several prominent Republicans.
The president on Friday invoked a "national emergency" to justify tapping military and other funds for barrier construction after Congress approved less than a fourth the US$5.7 billion he had sought for border security.
Miller, echoing Trump's arguments, said that an unsecured border allowed drugs and criminals to pour into the country. He dismissed government statistics showing illegal entries had fallen.
"You cannot have uncontrolled, unsecured areas of the border where people can pour in undetected," he said.
Xavier Becerra, the attorney general of California, told ABC his state would be filing a lawsuit against the project "definitely, and imminently."
He said California and other states had legal standing in the case because they risked losing money intended for military projects, disaster assistance and other purposes. Several states "will be harmed," he said.
Several Republican senators have decried the emergency declaration, saying it establishes a dangerous precedent and amounts to executive overreach.
One well-known Republican, former Massachusetts governor William Weld, is even entertaining a 2020 primary challenge to the president.
While his chances would appear slim, he argued Sunday on ABC that Americans cannot afford six more years of a president who "wants to divide the country" and is "reckless" in running up trillion-dollar deficits.
He said the emergency declaration was an example of Trump trying to "make himself seem indispensable," then added, "He's not indispensable at all."