Biden administration officials are weighing whether to toughen an asylum ban to maintain lower levels of illegal crossings at the U.S.-Mexico border since the ban went into effect in June, a U.S. Department of Homeland Security official familiar with the matter told Reuters.

The ban is designed to be lifted if the number of migrants caught crossing the southern border illegally drops below an average of 1,500 per day for one week, followed by a two-week waiting period.

The change under discussion would lengthen the time the number of people caught must remain below that level to several weeks, the DHS official said, requesting anonymity to discuss internal deliberations.

The 1,500 threshold has not yet been reached. In July, the U.S. Border Patrol apprehended an average 1,820 migrants a day. There was one day in December when the number reached 10,800, which officials at the time said was at or near a record.

The New York Times first reported the discussions. A DHS spokesperson said the department was reviewing public comments and could not comment on potential changes.

Illegal immigration is a top U.S. voter concern heading into the Nov. 5 election that will decide control of the White House and Congress.

Republican presidential candidate Donald Trump has promised mass deportations if reelected and criticized Vice President Kamala Harris' approach to border security as record numbers of migrants have been caught illegally crossing the border in recent years.

Harris, the Democratic nominee, has criticized Trump for opposing a bipartisan border security bill that failed in the U.S. Senate earlier this year.

President Joe Biden imposed the sweeping asylum ban on June 5, barring many migrants from seeking asylum if they crossed the southern border illegally.

The White House said the restrictions were needed after Republicans rejected the Senate bill and that migrants could use new Biden-era pathways to enter the U.S. legally.

The number of migrants caught illegally crossing the U.S.-Mexico border dropped to 56,000 in July, down from 118,000 in May, according to U.S. government figures.

The asylum ban was issued as an "interim final rule" by DHS and the Justice Department, meaning it still must be finalized.