WASHINGTON — Representative Steve King, Republican of Iowa, moved on Tuesday to block the Treasury Department’s sweeping plan to represent women and civil rights leaders on American currency, including the placement of Harriet Tubman on the $20 bill.

Mr. King filed an amendment to an annual appropriations bill that would prevent any money from being spent to redesign American currency. It is unclear whether it will ultimately get a vote when the full spending bill, which covers financial services and general government appropriations, comes before the House this week.

The congressman’s motivation for filing the amendment was also unclear. His office did not immediately respond to a request for comment. The amendment was first reported by The Huffington Post.

Mr. King is known nationally for his polarizing stance on illegal immigration. He has introduced legislation to revoke birthright citizenship for the children of undocumented immigrants. In 2013, Mr. King drew ire for saying that such children were likely to be drug mules with “calves the size of cantaloupes” from hauling marijuana.