Those overseeing Honolulu’s rail project worked on multiple occasions — and with various advocates — to sharpen their message for an eventual rail-tax extension well before it was publicly announced that the transit project faced a nearly $1 billion budget shortfall, documents show.

One of those advocates was Pacific Resource Partnership, the local trade group that several years ago played an integral role to ensure that the island’s elevated rail project would survive.

In emails sent Oct. 15 and 16, one of HART’s top government liaisons responded to a PRP request seeking information on the rail agency’s tax-related talking points. She also suggested that PRP send its own talking points on a potential rail-tax extension to HART for review.

“I can then walk in to discuss those points for fine tuning by our folks,” HART Government Relations Director Joyce Oliveira wrote to PRP’s then-director for advocacy and communications, Cindy McMillan. “It’s worth a try to get some focus on this issue.”

In January, McMillan left PRP to become Gov. David Ige’s communications director.

Those and other emails obtained by the Honolulu Star-Advertiser show that PRP has stayed in regular contact with HART following the trade group’s notable influence over the pivotal 2012 mayoral election won by Honolulu Mayor Kirk Caldwell. PRP has shared its polling data with rail officials, asked about how construction might affect its own board members and queried HART about measures that would ensure future rail construction.

The Honolulu Authority for Rapid Transportation says it relies on the group and other advocates of the most expensive public works project in state history for the insight they can provide. “Someone like PRP, who often has a much better pulse of the community, as well as some of the legislative process, is always helpful,” Deputy Executive Director Brennon Morioka said Thursday.

The October exchange with PRP took place about two months before a game-changing Dec. 18 HART board meeting, in which rail leaders first publicly disclosed that the project would face as much as a $910 million shortfall. The reasons they gave were skyrocketing construction costs, subpar revenue collections, and federal bus dollars that had been included in rail’s budget but were now deemed off-limits by local political leaders. They also proposed an extension of the GET surcharge to help climb out of that budget hole.

Rail officials, however, said that the October emails to PRP on a tax extension had nothing to do with the looming budget shortfall.

City officials had already planned to lobby state lawmakers for a rail tax extension just as they had in the previous legislative session, regardless of the fiscal crisis to come. Back in October, rail officials added, they still didn’t have a clear estimate of how deep rail’s budget hole would be and they didn’t brief PRP on it.

Still, PRP Executive Director John White said the trade group had rail’s potential budget problems in mind as it considered its strategy to lobby for a tax extension. The consortium of union carpenters and private contractors learned sometime around late summer or the early fall that rail could soon see a budget shortfall of some yet-to-be-determined amount, White said in an interview Thursday.

“When we learned that rail faced a shortfall we were very determined to work with rail advocates,” along with HART, to make sure it got the funding it needed to keep the project moving, White said.

It’s not clear what the talking points were. White said PRP’s were lost with McMillan’s departure, and rail officials said that their strategy changed once the scope of rail’s budget shortfall started to come into focus.

White and other PRP officials emphasized last week that they felt other rail advocacy groups played a more prominent role in working to extend the rail tax.

Previously disclosed correspondence has shown city and rail officials, along with project advocates, coordinating their message on the rail tax. “I just want to be sure we are all on the same page and saying the same thing,” Ray Soon, Caldwell’s chief of staff, wrote ahead of a meeting in a Nov. 20 email to rail officials and Jennifer Sabas, who serves as executive director of rail advocacy group Move Oahu Forward. White cited Move Oahu Forward as playing that more prominent role.

Ige authorized a five-year extension in July, and the Honolulu City Council is expected to vote on the matter in the next year.

For the 2012 mayoral race, PRP’s political action committee spent more than $3.6 million in ads, opinion polls and other outreach against former Gov. Ben Cayetano, who opposed the rail project. PRP supports the project on the basis it will provide construction and contracting jobs for the rail line and surrounding development. Last year, the group agreed to apologize to Cayetano to settle the former governor’s defamation lawsuit against PRP for its barrage of negative advertising against him during the mayoral campaign.

White in December 2013 asked HART officials to help answer questions for a PRP board member whose company lay along the future rail line.

“Was hoping I could connect him with someone at HART to discuss further,” he wrote to rail agency spokeswoman Jeanne Mariani-Belding. Mariani-Belding encouraged White to have the board member contact her and “we can go from there.”

White’s emails further showed that in April 2014 rail support and opposition on Oahu remained virtually deadlocked, with 47 percent supporting and 46 against the 20-mile elevated rail project.

“I’m concerned about leeward and central Oahu,” White wrote in an April 23, 2014, email to HART Executive Director Dan Grabauskas. Those areas had seen a dip in support, which White attributed to mostly state road repair work there and the subsequent traffic disruptions.

“I do however think … it’s a harbinger of things to come (potential big, short-term drops in support for rail) as construction impacts traffic in an area,” White further wrote to Grabauskas.

On Thursday, White said that PRP’s latest rail poll, taken in February, put support at 46 percent and opposition to the project at 50 percent.

“Things like traffic disruption can temporarily impact the public perception of rail,” White said Thursday. “If you’re facing an hour-and-a-half commute every day, you’re bound to be frustrated by it.” White said he expects support to rebound once rail operations begin.