The price tag of the stalled Thirty Meter Telescope has ballooned to $2.4 billion, while the final decision about where to build it might come within a few months.

TMT Vice President Gordon Squires said Monday that the increase from the previously estimated $1.4 billion cost is due to the construction delay, as well as inflation and world market cost increases for some construction items.

“We will not know the true cost of the project until we finalize a construction site and do an analysis,” Squires said in a statement.

Squires confirmed the statements of TMT officials who spoke at a National Academy of Sciences meeting in Washington, D.C., last week.

The meeting was the Panel on Optical and Infrared Observatories From the Ground, which is part of the Decadal Survey, convened by the National Academy of Sciences every 10 years to set priorities for astronomy and advise the government on where to allocate its funds.

According to a report on the meeting by The New York Times, Ed Stone, executive director of the TMT International Observatory (TIO), acknowledged disagreement among the project’s board of governors about where to build the telescope.

Asked whether the partners are committed to the project, even if it it had to be moved from Mauna Kea to the La Palma backup site in the Canary Islands, Stone responded, “Each member would have to agree to go to La Palma.”

He added, “We’re not there yet.”

Stone, an astrophysicist at Caltech, said the partners were hoping that new discussions and efforts in Hawaii, including the establishment of a proposed blue-ribbon reconciliation commission by the state Legislature, would lead to compromise by separating the dispute on Mauna Kea from broader conflicts.

If a compromise fails to materialize, Stone said, “I’m sure the partners will agree to go to La Palma.”

TMT project manager, Gary Sanders, told the committee that the project is “shovel-ready, just not shovel-accessible.”

Sanders, according to the Times, said Hawaii’s tallest mountain is the superior site but that the desired science could be conducted at either location. He added that a final decision is a few months away.

In his statement Monday, Squires said, “Regardless of the project cost increase, TIO as an organization has determined that Hawaii is still the preferred site for the Thirty Meter Telescope and remains committed to building in Hawaii.”

Last week’s meeting in Washington was the first chance astronomers had to plead their cases for funding in public. A final funding recommendation for space- and ground-based astronomy is expected next year.

Support by the National Academy of Sciences could lead to big money from the National Science Foundation, which has yet to contribute to either project.

The TMT has teamed up with another proposed mega-observatory, the Giant Magellan Telescope, planned for Chile, and together they asked the panel for support.

Under their proposal the National Science Foundation would contribute $850 million to each project. That would guarantee American astronomers about one-third of the observing time on the cutting-edge telescope, which would be 10 times more powerful than anything now on Earth.

Under questioning, however, officials from both projects admitted to being hundreds of millions of dollars short of the money needed to pay for their own shares for construction.

TMT partners India and China reportedly are pushing for a switch to the Canary Islands, while Japan has suspended funding for a year. Canadian astronomers have said they are willing to hold out for the superior viewing conditions of Mauna Kea.

In Hawaii the project has been stalled by legal and regulatory obstacles and regulatory hurdles over the last five years. The largely Native Hawaiian opponents have blocked construction since July while occupying the base of Mauna Kea.

If the TMT does abandon Hawaii for La Palma, it might not necessarily mean clear sailing. At least one Canary Islands environmental group, Ben Magec, has vowed to continue challenging the TMT in court.

If and when the TMT is allowed to start construction, it is expected to stretch over a full decade.