A federal district judge on Wednesday concluded that part of last year’s voter-approved Amendment 71 — which makes it harder to change the state constitution via ballot initiative — violates the U.S. Constitution.

Judge William J. Martinez’s order stops short of striking the amendment down but pledges to block a significant part of it from being enacted unless Colorado Secretary of State Wayne Williams can convince him otherwise.

If the judge follows through with an injunction, it could have significant consequences for the 2018 ballot. Some advocacy groups that are considering pursuing statutory ballot initiatives may change course and pursue constitutional measures. Meanwhile, those that are seeking constitutional changes would face a much easier path.

Amendment 71, dubbed “Raise the Bar” by supporters, lifts the threshold for passage of constitutional amendments to 55 percent of the vote. And, to get on the ballot, measures now need signatures from 2 percent of registered voters in all 35 state Senate districts.

Backers said the changes were long overdue, arguing that Colorado’s ballot access laws make it too easy to change the state constitution — which ranks among the longest and most convoluted in the country. And, they said, the Senate district requirement is needed to give rural Colorado more say in what goes on the ballot. Previously, signature gathering efforts have typically been concentrated within the major population centers of the Front Range.

Voters adopted it by a wide margin. But in April, opponents of the measure filed suit, arguing that the signature requirement violates the principle of “one person, one vote,” because Colorado’s Senate districts vary greatly in their voting populations. The court on Wednesday agreed, concluding that the signature requirement violates the 14th Amendment.

“Part of the new amendment process is constitutionally infirm,” Martinez concluded. “It is, however, severable from the remainder of the new requirements” — meaning the higher vote threshold needed for passage can stand.

The lawsuit was brought by a number of advocacy groups, including the Coalition for Colorado Universal Health Care and ColoradoCareYes — both of which are behind Amendment 69, the failed 2016 ballot measure that would have created a single-payer health care system in Colorado.

Their argument rested on the idea that, while Colorado’s 35 Senate districts were designed to be roughly equal in population, they don’t have the same numbers of registered voters. Senate District 23, for instance, had 51,723 more registered voters at the start of 2017 than District 21, according to the lawsuit — a gap of 60 percent. That, they argued, gives the typical District 21 voter more influence in the signature gathering process than a voter in the larger district.

Martinez gave the state until March 9 to provide “empirical data” showing that the districts weren’t causing vote dilution. Otherwise, the order suggests, a permanent injunction and final judgment would be issued against the state.

Suzanne Staiert, the deputy secretary of state, said her office would “defend the vote of the people,” but hasn’t decided whether to respond to the judge’s data analysis or challenge the eventual ruling on appeal.