U.S. President Donald Trump on Thursday ordered the Commerce Department to begin work on a new census that excludes immigrants in the U.S. illegally, revisiting a push from his first term that was later rejected by the courts and reversed by his successor.

Trump made his census order in an early-morning post on Truth Social, saying the population count carried out every 10 years should be "based on modern-day facts and figures" and results of the 2024 presidential election.

"People who are in our Country illegally will not be counted in the census," he said.

Trump's politicisation of a constitutionally required process used to determine congressional districts and federal funding comes as the president has pushed Republicans in Texas and several other states to pursue a rare mid-decade redistricting for partisan gain.

The next full census is planned for 2030. The White House had no immediate comment on whether Trump was calling for a count before the 2030 census.

Trump has long railed against the inclusion of immigrants living in the U.S. illegally from the census, which is used to determine the number of seats each state gets in the U.S. House of Representatives and state legislative districts.

The U.S. Supreme Court in 2019 blocked Trump from adding a contentious citizenship question to the 2020 census, saying the federal government gave a "contrived" rationale.

Upon taking office in 2021, former President Joe Biden used an executive order to affirm the longstanding practice of including all people residing in a state in the official count. Trump revoked that order on his first day in office this term.

Sean Moulton, a census expert at the watchdog group Project on Government Oversight, said some Republicans believed excluding immigrants in the U.S. illegally would benefit Republican districts and hurt urban areas, which are often Democratic-controlled.

But Moulton said not counting all the people living in a given region hurts everyone there.

"If we don't count everybody, we wind up misspending our money on infrastructure and hospitals, schools, power grids and water, so everyone winds up being inconvenienced and encountering problems," he said.

Trump's announcement comes amid pressure by Republicans to redraw congressional districts in Texas, Florida, Missouri and Ohio, and with Democrats now threatening to redistrict their own voting maps in California, Illinois and New York.

Undertaking an additional census would be time-consuming and costly. The 2020 census cost nearly $14 billion, according to the U.S. Government Accountability Office.

Trump has also launched a nationwide campaign to arrest migrants who are in the country illegally and to deport millions of people, actions that have prompted dozens of lawsuits.