U.S. President Donald Trump will sign a border security bill to avert another government shutdown but also declare a national emergency to secure funds for a southern border wall without congressional approval, the White House said Thursday.

"President Trump will sign the government funding bill, and as he has stated before, he will also take other executive action -- including a national emergency -- to ensure we stop the national security and humanitarian crisis at the border," press secretary Sarah Huckabee Sanders said.

"The president is once again delivering on his promise to build the wall, protect the border, and secure our great country," Sanders said in a statement.

Congress is expected later Thursday to approve the bill, which includes $1.375 billion for 55 miles (88 kilometers) of fencing and other physical barriers at the border with Mexico -- an amount that is far short of the $5.7 billion Trump had demanded for more than 200 miles of steel and concrete wall.

With the national emergency declaration, Trump would reallocate additional federal funds to deliver a signature promise in his 2016 presidential campaign. But such action would draw a court challenge from Democrats.

Passage by the Democratic-controlled House of Representatives and the Republican-led Senate will set the stage for Trump to sign the bill into law before the midnight Friday deadline for another partial government shutdown.

Trump's demand for $5.7 billion in funding for the wall led to a 35-day partial government shutdown through Jan. 25, the longest in U.S. history.