Montana Republican Sen. Steve Daines is set to introduce legislation on Wednesday that would require the census to include a citizenship question, Fox News has learned, in an aggressive new effort that could bolster the Trump administration's legal case for querying residents on their citizenship status.

With just weeks to go until the Census Bureau’s July 1 deadline to print out the forms, the Supreme Court is expected to rule on the legality of the Trump administration's decision to add a citizenship question to the 2020 census in June. The decision will affect how many congressional seats states have and how federal dollars are distributed for years to come.

A majority of justices signaled during oral arguments that they would vote in favor of the White House, but Daines' legislation -- while facing slim chances in the Democrat-controlled House -- would aim to improve the chances of a citizenship question appearing on the census after the Trump administration ends.

"This is America," Daines told Fox News. "We are a sovereign nation. It's absurd that we don't know how many citizens and non-citizens are living in this country. That's why I'm introducing this bill to require a citizenship question on the census - and ensure that states harboring millions of illegal immigrants are not rewarded with additional taxpayer dollars."

Last October, Daines pressed now-Census Bureau director Steven Dillingham on the citizenship question, telling Dillingham, “Montana should have more of a say in Washington, D.C., than illegal immigrants harboring in sanctuary cities across the country." Dillingham demurred.

Sen. Steve Daines, R-Mont., said he is optimistic that changes could be made to the tax reform bill that would get him on board with the plan. (Reuters/Larry Downing)

"It makes no sense why a state like California that harbors millions of illegal immigrants is rewarded with additional representation in Congress and taxpayer resources at the expense of more rural states like Montana," Daines told Fox News at the time. "That is rewarding illegal behavior."

Daines added, "It is common sense for a sovereign nation to know how many citizens and noncitizens are in the country."

TRUMP: CENSUS 'MEANINGLESS' WITHOUT CITIZENSHIP QUESTION

The Trump administration has argued that it has wide discretion in designing the questionnaire and that the citizenship question is clearly constitutional because it has been asked before — most recently, 1950 — and continues to be used on smaller, annual population surveys.

"It is common sense for a sovereign nation to know how many citizens and noncitizens are in the country."
— Montana Republican Sen. Steve Daines

Progressives, however, warn that a citizenship question would improperly discourage many illegal immigrants from answering their census forms. That result, in turn, would likely cost Democrats a slew of congressional seats, which are apportioned based on census results that include all people in a district -- whether or not they are citizens. (Some legal scholars, including Chapman University law professor John Eastman, have argued that the Constitution does not require counting non-citizens.)

In immigrant communities often wary of government, a question about citizenship status will make people "less likely to fill out the census form or even answer the door when someone comes knocking," said Esperanza Guevara, who works for the Coalition for Humane Immigrant Rights of Los Angeles.

"Their first thought is, 'Is this information going to be used against me?'" Guevara added.

However, Census Bureau chief Ron Jarmin said the agency is legally barred from sharing its information with law enforcement agencies: "We are committed to ensuring that the data we collect are always protected."

California Attorney General Xavier Becerra, in a statement earlier this year, said the issue was critical in his state. California, heavily liberal, is estimated to have far more illegal immigrants than any other state. California is also the home to more Hispanics than any other state.

“California simply has too much to lose to allow the Trump administration to botch this important decennial obligation," Becerra said. "What the Trump Administration is requesting is not just alarming, it is an unconstitutional attempt to disrupt an accurate census count.”

The Public Policy Institute of California has said that failure to accurately tally immigrants and other hard-to-reach groups could lead to an undercount of 1.6 million people, or roughly 4 percent of the state's population. That would be enough to cost California one of its 53 House seats.

Nearly three in four Californians belong to groups the census has historically undercounted, including Hispanics, blacks, renters, immigrants, children and members of multiple families that share a single home. The state also has an above-average poverty rate, and the poor — especially the homeless — are difficult to count.

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Given the approaching census, California has picked a bad time for its slowest growth rate in history. New estimates released Wednesday by state officials say California grew by 0.47 percent in 2018, the slowest rate on record dating back to 1900.

California's population has been creeping toward 40 million people, viewed as a milestone for a state that began as a frontier outpost and now boasts the world's fifth largest economy. Texas at No. 2 is still shy of 30 million people. But state officials on Wednesday noted the latest estimates could temper expectations for robust growth as births decline, deaths rise and immigration slows.

The Associated Press contributed to this report.