Civil rights groups will urge a U.S. judge on Monday to temporarily halt an order by President Donald Trump that bars asylum for migrants who illegally cross the border with Mexico.

The groups argued in court papers that Trump’s Nov. 9 order violated administrative and immigration law.

The hearing before U.S. District Judge Jon Tigar in San Francisco comes as thousands of Central Americans, including a large number of children, are traveling in caravans toward the U.S. border to escape violence and poverty at home. Some have already arrived at Tijuana, a Mexican city on the border with California.

Trump cited an overwhelmed immigration system for his proclamation that officials will only process asylum claims for migrants who present themselves at an official entry point.

Immigration advocates said the order clearly conflicted with the Immigration and Nationality Act, which allows any person present in the United States to seek asylum, regardless of how they entered the country.

The groups also argued that the administration violated a requirement to provide a period of time for public comments before the order took effect.

Any ruling on Monday would likely be procedural and would restore the prior asylum rules while the rights groups made their case for a preliminary injunction at a future hearing.

The lawsuit was brought by the American Civil Liberties Union, the Southern Poverty Law Center and the Center for Constitutional Rights.

Tigar was nominated to the court by President Barack Obama.

Rights groups have said immigrants are being forced to wait days or weeks at the border before they can present themselves for asylum, and the administration has been sued for deliberately slowing processing times at official ports.

Caravan participants began to arrive last week in Tijuana on the Mexican side of the U.S. border, which has put a strain on humanitarian shelters where many will wait to seek asylum. Their presence has also strained Tijuana’s reputation as a welcoming city, with some residents screaming at the migrants, “Get out!”

Trump sent more than 5,000 soldiers to the 2,000-mile (3,100 kilometers) frontier with Mexico to harden the border, although critics dismissed the move as a political stunt ahead of Congressional elections on Nov. 6.