HELENA — A constitutional dispute between Montana’s Democratic governor and Republican secretary of state escalated on Friday when a judge issued a temporary restraining order blocking Secretary of State Corey Stapleton from enrolling into state law a bison bill that Gov. Steve Bullock vetoed in April.

District Judge James Reynolds’ order comes two days after Stapleton declared that House Bill 132 had become law despite the governor writing an April 29 veto letter, which was posted on the Montana Legislature’s website. Stapleton said Bullock missed a 10-day deadline to physically turn the veto in to the secretary’s office.

Bullock said no such deadline exists and that he followed the law and constitution in issuing the veto on the bill, which would change the definition of “wild bison.” The governor filed a lawsuit Friday after Stapleton assigned the bill a chapter number, which is the first step toward codifying and publishing it into state law.

The disputed bill would redefine a wild bison or wild buffalo in a way that Bullock said in his veto letter would create confusion and uncertainty about whether Yellowstone National Park bison could be mistakenly considered domestic animals. The governor suggested changes to the bill that lawmakers rejected.

Reynolds acted swiftly after receiving Bullock’s complaint. The judge wrote in his order that if what the governor says is true, Stapleton is trying to unconstitutionally override a governor’s veto, which would cause irreparable harm because the vetoed law would go into immediate effect.

“The Governor has established facts, which, if proven true, establish he vetoed HB 132 in compliance with the Montana Constitution and Montana Code Annotated,” Reynolds wrote.

The judge ordered Stapleton to rescind the chapter number he assigned the bill, remove the bill from the file of laws passed during this year’s legislative session and inform the Legislature’s code commissioner that he had done so. The judge also ordered Stapleton to send the governor’s veto message and a copy of the bill to all legislators within five days.

Stapleton did not immediately return a call for comment. His agency’s attorney, Austin James, said the secretary’s office would comment only after reviewing the court documents.

The clash of powers between the two elected offices comes as Stapleton makes his second attempt for the Republican nomination for governor — he lost in 2012 — while Bullock, who can’t run again due to term limits, seeks the Democratic nomination for president.

On Wednesday, Stapleton told The Associated Press that two state laws justified his actions. The first says the governor must return the vetoed bill to the secretary of state if the Legislature is not in session. The second says that a bill that has not been returned by the governor within 10 days after its delivery to the governor becomes law.

Stapleton said the vetoed bill wasn’t delivered to his office until May 22.

Bullock said Stapleton is misinterpreting the law. The governor cited the state constitut ion, which says a bill only becomes law if the does not sign or veto it within 10 days after it is delivered to the governor. The Legislature transmitted the bison bill to the governor on April 25, and Bullock’s veto letter came four days later.

“When the Governor of Montana vetoes a bill, the Montana Secretary of State cannot ignore the veto and make the bill a law,” Bullock attorney Raphael Graybill wrote in the lawsuit. “Unless the legislature overrides the Governor’s veto, the bill does not become law. There are few principles more basic to our constitutional system of ordered lawmaking.”

Graybill said a court hearing on the temporary restraining order has not yet been set.