WASHINGTON — Facing mounting political pressure over the migrant influx at the U.S. southern border, President Joe Biden on Tuesday signed an executive order that will temporarily shut down asylum requests once the average number of daily encounters tops 2,500 between official ports of entry, according to a senior administration official.

The shutdown would go into effect immediately since that threshold has already been met, a senior administration official said. The border would reopen only once that number falls to 1,500. The president's order would come under the Immigration and Nationality Act sections 212(f) and 215(a) suspending entry of noncitizens who cross the southern border into the United States unlawfully. 

Senior administration officials said Tuesday in a call with reporters that "individuals who cross the southern border unlawfully or without authorization will generally be ineligible for asylum, absent exceptionally compelling circumstances, unless they are accepted by the proclamation."