Texas Gov. Greg Abbott told Chicago's mayor he'll continue to bus migrants out of Texas 'until Biden secures the border'

• Texas Gov. Greg Abbott said in a letter he'd continue bussing migrants out of Texas to sanctuary cities.
• The letter came after Chicago's mayor pleaded with him to stop sending migrants to the midwestern city.
• A COVID-era policy that's been used to expel more than 2 million migrants expires soon.

In a letter on Monday, Texas Gov. Greg Abbott told Chicago Mayor Lori Lightfoot he'd continue to bus migrants out of Texas "until Biden secures the border."