JUNEAU — The state could face some difficult decisions, and tight budgets, as it pursues a major liquefied natural gas project.

Revenue Commissioner Angela Rodell told the House Resources Committee on Wednesday that if the state pursues the gas treatment plant and pipeline project without TransCanada Corp. as a partner, Alaska’s share of project costs could be more than half the state’s unrestricted general fund revenue near the start of construction, around 2020.

With TransCanada involved, the state could be giving up about $300 million in annual revenue once gas started to flow, Rodell said. While there’s more upside to going it alone, she said that option presents high risks. The cost of that lost revenue, she said, “is worth the insurance policy basically.”

Lawmakers are considering legislation aimed at moving the mega-project into the phase of preliminary engineering and design. The state is mulling an equity stake of 20 percent to 25 percent, which would be determined by its royalty share and the gas tax rate, which would be set in the bill.

The bill speaks to terms already agreed upon by state officials and TransCanada, the Alaska Gasline Development Corp., or AGDC, and the major North Slope players: BP PLC, ConocoPhillips and Exxon Mobil Corp. The agreements are subject to passage of enabling legislation deemed acceptable by the parties.

The state has signed a separate agreement with Trans-Canada to manage its interest in a gas treatment plant and pipeline. While the state would have an equity buy-back option, the arrangement is seen as a way for the state to not have to shoulder as much in upfront costs as it would without TransCanada.

The agreement also would serve as a transition from the Alaska Gasline Inducement Act. TransCanada has been pursuing a pipeline with Exxon Mobil for years under that law, but Gov. Sean Parnell has said it no longer fits with the current situation.

For a project estimated at $45 billion to more than $65 billion, the state’s share will be significant. While estimates have been somewhat fluid, information provided to the committee Wednesday showed that with a 20 percent stake, the state was looking at a potential equity investment of $5.6 billion to $11 billion. The lower end reflected Trans-Canada’s involvement and the higher end is if the state goes it alone.

While the cash terms look daunting, Rodell said, the project is worth pursuing because of the potential revenue it could bring the state. She said the state can mitigate its exposure through different financing options and possibly even bringing in new partners.

Rep. Craig Johnson, R-Anchorage, said one of the reasons the companies have seemed excited is that the state has expressed willingness to put “skin in the game.” But he said he keeps hearing that the state is “peeling that skin off” by pursuing partners. He said he would like to know from the companies at what level the current alignment on a project could be lost.

The figures used in Wednesday’s presentation did not take into account the potential future costs of other big-ticket projects the state has been pursuing.

It also didn’t look at the cost of things like roads needed for work on the gas line project or the demands on state services by project workers and their families.

Questions also were raised about potential cost overruns and how much would be left in the state’s savings accounts as the state looks to finance the project.

Rep. Geran Tarr, D-Anchorage, asked if the state might be in a situation of “optimism bias.”

Rodell said there may be some of that. But she said a lot of that has to do with the companies being willing to work with the state in a way they haven’t before, and seeing a potential to commercialize gas.

“I think we have to take advantage of that while we can, learn what we can from this project and recognize that we may be suffering from a little bit of optimism bias and it may not go forward in 2015 for other reasons. But I think we owe it to Alaskans and we owe it to ourselves to at least get through the next stage,” she said.

There are built-in decision points as plans proceed, and no guarantee a project will be built.

Earlier in the day, in the Senate Finance Committee, Bill McMahon Jr., an executive with ExxonMobil Production Co., said the parties behind the project hope to file an export-license application later this year. He said a license would need to be in hand for the parties to make a final investment decision around 2018 or 2019.

An issue raised during that hearing was whether a federal loan guarantee was still on the table. Larry Persily, the federal coordinator for Alaska gas pipeline projects, said in an interview it was not.

Persily said the $18 billion loan guarantee, passed in 2004 and adjusted for inflation, applied only to a line that would serve North American markets. While that had been a focus of TransCanada under the inducement act, the project now being pursued, because of market changes, would allow for liquefied natural gas exports overseas.