US Customs and Border Protection

Updated July 19 at 12:25 p.m. ET

Mark Morgan, acting head of Customs and Border Protection, said on Thursday that his agency is rolling out the Trump administration's new asylum rule as a small "pilot" for now but that officials expect it to be blocked in court.

Vice President Mike Pence and members of Congress will visit the Rio Grande Valley later this week.

Customs and Border Protection has launched an investigation into a secret Facebook group for current and former Border Patrol agents in which members posted derogatory remarks targeting migrants and lawmakers.

Federal immigration authorities say they arrested 52 people in Central and South Texas last week.

The arrests came before telegraphed operations in 10 major cities, including Houston, that President Donald Trump had touted. The president tweeted Saturday that he would delay the large-scale raids to give Congress time to make adjustments to U.S. asylum laws.

Gov. Greg Abbott announced Friday that the state will deploy 1,000 troops from the Texas National Guard to the U.S.-Mexico border to aid the federal government with border security efforts.

Over the past three months, the number of Central Americans arriving at the U.S.-Mexico border has jumped exponentially, and total border crossings have reached levels last seen in 2006.

The Congressional Hispanic Caucus held a press conference Tuesday afternoon to discuss the death of a migrant minor at the Weslaco Border Patrol station.