The fight over whether Kansas Secretary of State Kris Kobach violated the constitution in his quest to demand proof of citizenship from voters goes to trial, with a ruling Wednesday that could complicate his case, in March.

A federal judge tossed aside some testimony Kobach had hoped to present in his long-running contention that voter fraud is commonplace. The decision came the same day President Donald Trump scrapped a commission, led by Kobach, designed to document what both men have said is widespread cheating at the polls.

In a statement, the White House said states were refusing to cooperate with the commission’s work. The panel also faced numerous lawsuits from civil rights groups.

Evidence thrown out Wednesday by a U.S. District Court judge in Kansas included some testimony from Hans von Spakovsky, another member of Trump’s voter fraud commission.

The court said von Spakovsky lacks direct knowledge or academic training related to some of his claims, including that a survey shows Kobach’s citizenship law isn’t a burden on voters.

“It is clear that von Spakovsky is not qualified to testify as an expert about this survey,” Judge Julie Robinson wrote.

A spokeswoman for Kobach didn’t respond to a request for comment late Tuesday afternoon.

The American Civil Liberties Union, which is representing the League of Women Voters and other plaintiffs in the lawsuit against Kobach, had attacked von Spakovsky’s credentials and methodology.

“We’re certainly pleased,” ACLU attorney Doug Bonney said.

Yet over the ACLU’s objections, von Spakovsky will testify on other matters related to voter fraud. And Kobach will get to keep expert testimony from Jesse Richman, a political science professor at Old Dominion University in Virginia.

Kobach says Richman’s research indicates voting by non-citizens is a substantial problem. But many other studies suggest that voting by non-citizens is remarkably rare

It’s unclear what weight the court will give to Kobach’s experts. The two sides will battle that out at trial.

By Celia Llopis-Jepsen, KCUR.