(NewsNation) — A fourth busload migrants arrived in Washington, D.C., over the holiday weekend as the Department of Homeland Security warned that the 8,000 migrants being taken into custody every day could more than double by the end of the month, when Title 42 expires.

Republican Texas Gov. Greg Abbott, frustrated with Biden administration immigration policies, vowed to send buses of migrants to the nation’s capital for processing. He has also conducted truck inspections at border checkpoints that have brought cross-border traffic to a halt.

Facing re-election in November, Abbott is drawing a hard line at the border, where he vows to halt what he says is the danger of migrants coming across in increasing numbers. Abbott is a staunch backer of former President Donald Trump, and backed Trump’s border wall plan strongly.

Title 42 is a Trump-era policy drawn from a 1944 public health law meant to inhibit the spread of communicable disease. It allows the U.S. to deport migrants from any country where a communicable disease is present, which during the COVID-19 pandemic applied to most of the world. Despite criticism from progressives, President Joe Biden kept the policy in place for more than a year after he took office.

Now, however, Title 42 is set to expire at the end of the month. However, many Republican lawmakers and even some moderate Democrats are fighting to keep that from happening.