The Hawaii Legislature has scheduled a special session Aug. 28-Sept. 1 to try again to reach a deal on funding the remainder of Honolulu’s 20-mile rail project, now estimated to cost $10 billion.

Senate President Ron Kouchi and House Speaker Scott Saiki sent a memo out Friday asking lawmakers to refrain from out-of-state travel during that week.

“Negotiations between the Senate and House have occurred for some time and are ongoing,” the memo says. “We are optimistic that the lead committee chairs have held, and will continue to hold, productive discussions.”

The special session’s purpose is to address rail financing and Honolulu’s adherence to its grant agreement with the Federal Transit Administration, according to the memo.

The FTA is kicking in $1.55 billion for the project. It could withhold some of those funds, particularly if the rail line has to stop short of its plan to go from Kapolei to Ala Moana Center. The project was expected to cost $5.2 billion just a few years ago.

Saiki said last month that the city’s latest figures projected a $1.384 billion shortfall from now to 2024. That’s up to $200 million more than what the city had indicated during the regular session, which ended May 4.

The special session is subject to final confirmation and lawmakers agreeing on proposed language for a bill or bills to be discussed, the memo says.

The two chambers ended the session far apart. The Senate left with a bill to extend Oahu’s 0.5 percent general excise tax surcharge for 10 years, until 2037, to help complete the rail project. That’s the option Honolulu Mayor Kirk Caldwell and the tourism industry support.

The House pushed a bill that would have allowed the GET surcharge to be levied for just one additional year, to 2028, while increasing the state’s 9.25 percent transient accommodations tax for 10 years.

Caldwell said in a statement Friday that he was “pleased” that the Legislature has scheduled a special session. He said he looks forward “to working with lawmakers in both the House and Senate on a sound financing mechanism that allows the city’s rail line to be built all the way to Ala Moana with all 21 stations.”

Read the legislative leaders’ memo below.