Private Property Owners

If the festering tension in South Texas over the last decade is any indication, some of the most strident opposition to Mr. Trump’s wall is expected to come from owners of land along the border who face seizure of their property by the federal government to build it.

Landowners in Texas, largely in the Rio Grande Valley, filed hundreds of lawsuits aiming to block the Bush administration from building fencing along the border. Some property owners opposed the government’s seizure of their land, while others said the compensation offered by federal authorities was too low.

Attention may now shift farther west to El Paso. Broad criticism of Mr. Trump in that city, a Democratic bastion in a state otherwise largely dominated by Republicans, emerged in recent days over the president’s widely discredited claim that border fencing had reduced crime there.

El Paso County, which encompasses the city of El Paso and is home to about 800,000 people, joined the Border Network for Human Rights; Protect Democracy, a group aiming to curb authoritarian-style politics; and the Niskanen Center, a nonpartisan think tank, in preparing a lawsuit over Mr. Trump’s declaration.

Ricardo Samaniego, who heads the governing county court of commissioners, said that Mr. Trump’s emergency declaration “will further damage El Paso County’s reputation and economy, and we are determined to stop this from happening.”

Precedent suggests that those living in the path of the planned wall may have a difficult time challenging it in court: Landowners have lost nearly all of the earlier cases aimed at preventing the federal government from seizing their property, though some ended up securing more compensation than initially offered.

Political Opponents

Democratic leaders in Congress have vowed to overturn the emergency declaration. “This is plainly a power grab by a disappointed president, who has gone outside the bounds of the law to try to get what he failed to achieve in the constitutional legislative process,” Speaker Nancy Pelosi of California and Senator Chuck Schumer of New York, the minority leader, said in a joint statement.