Sixteen blue states as well as several localities are seeking to defend the current system of doling out U.S. House seats among states, which is being challenged in federal court in Alabama.

In a motion to intervene filed Monday, the states suggested the Trump administration could not be depended on to whole-heartedly defend the Census Bureau’s policy of including undocumented immigrants in its count for congressional apportionment.

The case has so far proceeded under the radar. But if successful, the lawsuit would be an incredible power grab by Republican states to counteract the shifts in demographics that favor bluer, more immigrant-friendly parts of the country.

The state of Alabama and Rep. Mo Brooks (R-AL) brought the lawsuit last year seeking an order that the Census Bureau exclude undocumented immigrants from the count that the Census Bureau provides for congressional apportionment, which also determines how many Electoral College votes each state gets in the presidential election.

The lawsuit has appeared to be a long-shot given that the Constitution mandates apportionment based on “whole number of persons in each state.” That language has been nearly universally interpreted to mean persons regardless of citizenship or legal status.

However, it took on new importance last month when Attorney General Bill Barr alluded to it in remarks in the Rose Garden announcing that, despite the administration’s loss on the citizenship question, it would still collect citizenship data based on existing records. Barr said the citizenship data could be “relevant” depending on how the “dispute” was resolved and that the administration “will be studying the issue.”

The Justice Department is ostensibly defending the Census Bureau’s current rule. However, the judge overseeing the case himself noted in an opinion on a procedural matter that the government’s defense seemed “rather halfhearted.”

The states and cities seeking to intervene pointed to both Barr’s comments and the judge’s “halfhearted” remark as reason to allow them to get involved. They also noted the federal government’s failure to bring up a particular defense to the lawsuit: specifically that the argument Alabama is now asserting for excluding undocumented immigrants was not among those presented to the Census Bureau during the notice-and-comment period for the current regime.

Suspicions that President Trump’s Justice Department could not be trusted to defend the Bureau’s current policy have long lingered and already some individual voters and local governments have successfully intervened to defend the inclusion of undocumented immigrants in the count.

The states that are seeking to join those defendant-intervenors are New York, California, Colorado, Connecticut, the District of Columbia, Illinois, Massachusetts, Minnesota, Nevada, New Jersey, New Mexico, Oregon, Rhode Island, Vermont, Virginia and Washington. Nine cities and counties also joined the new motion to intervene as did the US Conference of Mayors

Read the motion to intervene below: