U.S. Rep. Doug Lamborn has his day in court Monday in Denver, when a federal judge has scheduled a hearing over a lawsuit that could determine whether the six-term Republican can appear on the June primary ballot.

Lamborn sued Secretary of State Wayne Williams in U.S. District Court this week in response to a unanimous Colorado Supreme Court ruling handed down Monday that ordered Lamborn’s name stricken from the primary ballot because hundreds of signatures on his nominating petitions were collected by someone who doesn’t qualify as a Colorado resident, contrary to state law.

The lawsuit argues that the residency requirement is unconstitutional because it restricts the First Amendment rights of a candidate’s supporters.

The hearing before Judge Philip Brimmer is set for 9 a.m. Monday at the Alfred A. Arraj United States Courthouse in Denver.

On Friday, Williams filed a motion to block the proposed intervention in the federal lawsuit by a group of GOP legislators – including state Sen. Owen Hill, one of the four challengers seeking to unseat Lamborn in the primary – and the five El Paso County Republican voters whose lawsuit resulted in this week’s supreme court decision.

“The proposed intervenors do not believe their interests are being adequately represented by the Secretary of State’s office and have different interests than the Secretary in protecting Colorado’s petition process,” said Kyle Fisk, a spokesman for the attorneys representing Hill and the others.

Deputy Secretary of State Suzanne Staiert agreed that the interests of the state and the Republicans seeking to join the lawsuit weren’t the same but insisted her office would vigorously defend the constitutionality of the residency requirement.

“Wanting to throw someone off the ballot isn’t the same thing as wanting to defend a state law,” she told Colorado Politics on Thursday.

In an interview Friday, Staiert pushed back against arguments contained in court documents filed by the proposed intervenors.

“We will defend the case when it gets to federal court. We have attorneys that are very good, that are the best in the state. They will defend state law whether or not this office philosophically disagrees with it,” she said.