SALT LAKE CITY — The battle is heating up once again between legislative leaders and Gov. Gary Herbert over the special election process for filling Rep. Jason Chaffetz's seat in Congress.

House Speaker Greg Hughes, R-Draper, will speak Tuesday about "concerns related to separation of powers" at a special meeting of all House members, while Senate Republicans and Democrats are set to caucus separately on the same topic.

Lawmakers, already frustrated that the governor chose last month not to call a special legislative session about the election, are now fuming because he stopped Attorney General Sean Reyes from giving them a legal opinion on the process.

Senate President Wayne Niederhauser, R-Sandy, said that actually happened several weeks ago but wasn't widely known until the story was circulated at Saturday's Republican and Democratic conventions to nominate candidates to replace Chaffetz, R-Utah.

"We weren't wanting to make a big deal of it right now. We wanted to let the elections process function," Niederhauser said Monday.

The Senate GOP, he said, "won't want to put a wrench in the spokes for that special election."

The election will include an Aug. 15 primary with three Republicans on the ballot: former legislator Chris Herrod, nominated at convention; and Provo Mayor John Curtis and Alpine lawyer Tanner Ainge, who gathered voter signatures.

Democrat Kathie Allen, who hopes to represent the District 3 seat held by Chaffetz since 2008, was nominated at her party's convention but has no primary opponents, meaning she will be on the November ballot.

The Republican supermajority in both the Utah House and Senate were split on the issue last session but recently backed giving the political parties sole power to choose the candidates for the special election, eliminating the signature-gathering path.

But the governor insisted the first congressional vacancy since 1929 be filled through the regular election process, which allows candidates to bypass the traditional caucus and convention system under a controversial law known as SB54.

Last month, lawmakers said Herbert doesn't have the authority to make the call because state law doesn't spell out how to handle a congressional vacancy. They stopped short, however, of saying they would mount a legal challenge.

The possibility of going to the Utah Supreme Court to order the attorney general to release an opinion is expected to be discussed by legislative attorneys at Tuesday's meetings.

Niederhauser, however, said he sees little interest in any action that could delay the election, even though he agrees the separation of powers issue between the governor and the Legislature needs to be resolved.

That will probably have to wait until the 2018 Legislature, the Senate president said.

Rep. Dan McCay, R-Riverton, who suggested last month that House Republicans consider threatening legal action against the governor to protect legislative prerogative, said Monday he doesn't believe leadership wants a court fight.

"In the question of legislators versus the governor, it's very rare when things get that bad. But it is unusual for the governor to usurp legislative prerogative," McCay said, including to seek opinions from the attorney general.

Paul Edwards, the governor's deputy chief of staff, said the attorney general's office has been working on issues related to the special election alongside the state Elections Office, overseen by Lt. Gov. Spencer Cox.

"It's important that the attorney general's office not compromise its attorney-client relationship with the executive branch," Edwards said. "When these questions came up, we chose not to waive our privilege. That's not being obstructionist."

He said legal action by the Legislature is not anticipated, but if that did happen and the attorney general's office had provided an opinion, the governor's office would have to hire outside counsel.

"It just seems like an odd thing," Edwards said. "We have real fires destroying property and threatening lives around the state. We don't need manufactured fires because there's no real issue to argue about at this point."

The Legislature has its own attorneys, he said, and if there is "some sort of legal problem with this, it needs to get to court fast" to be fair to the candidates and voters "involved in what we think is a very fair and orderly process."

Edwards said elections officials have consulted with a number of sources, including the U.S. House of Representatives, on issues such as whether the process to fill a congressional vacancy can begin before a representative leaves office.

Six states have done so since 2001, Edwards said.

Chaffetz announced last month he would step down June 30 for a position in the private sector, believed to be with Fox News. The special election is for the remainder of his term through December 2018.

Reyes' office had little to say about its role in the increased friction between the governor and lawmakers.

"We don't generally comment on our client communication," said Dan Burton, the attorney general's spokesman. "In this case, the client is the governor."

Herbert is scheduled to tour the fire damage in southern Utah on Tuesday.

The rift may be about more than separation of powers.

The Legislature's special election plan would have ignored SB54, passed in 2014 as a compromise to stop the Count My Vote initiative that would have replaced the caucus and convention nomination system with a direct primary.

"There seems to be some erosion of their willingness to maintain the solution," Count My Vote leader Rich McKeown said.

The group is "in observation mode," he said, but would bring back the initiative if necessary.

"That would require signficant amounts of money," McKeown said. "But we've always said we are going to be protective of people's right to vote."