Democrats oppose the presence of a citizenship question on the 2020 census because it will expose how many people in the U.S. are either non-citizens or here illegally, according to Rep. Jim Jordan, R-Ohio.

"I think they are a little nervous about what the number may be," Jordan said Tuesday on "Tucker Carlson Tonight." You actually may find out how many people -- maybe it's not 11 million, the number we hear all the time. Maybe it's a higher number of people who are here who aren't citizens or here in some illegal fashion."

TED CRUZ: CITIZENSHIP QUESTION ON CENSUS IS 'BASIC COMMON SENSE'

The decennial census delineates congressional districts by population, meaning anyone counted in the census adds to that apportionment, the congressman added.

In addition, host Tucker Carlson questioned why the Democrats, the self-described "party of science" would be against "gathering data."

"They have no real explanation for that," said Carlson, who added that other countries, including neighboring Canada, have a citizenship question on their census and are not deemed "racist."

In response, Jordan remarked that the "racism" claim was what opponents "use all the time when they want to accuse us of things they disagree with or want a different policy."

CLICK TO GET THE FOX NEWS APP

"[Supreme Court Justice Samuel] Alito said it best -- no one disagrees that it's important to know how many immigrants are in your country," said Jordan, who added the question has been included in most census tallies going back to the Monroe administration.

"In one form or another, it's been asked for 200 years," he said. " ...This is ... so common sense."