The MTA on Wednesday said that the agency must soon settle on an exact opening date for the Second Avenue subway—and Dec. 31, 2016, would be a fairly difficult one.

Citing logistical and security issues relating to the fact that the opening of the line’s first phase is slated to fall on New Year’s Eve, MTA Chairman Tom Prendergast said that the opening, set seven years ago, would provide “another set of challenges” for the agency.

“We do need to set a date at which time we say ‘we’re a go’ or ‘not a go,’” said Prendergast after the agency’s board meeting. “We’re approaching that point. There’s been a tremendous amount of focus, more so than I can ever remember, about trying to make the committed date of Dec. 31 — for a lot of good reasons. So stay tuned.”

The agency remains positive that construction will wrap up in time to open before the year’s end—just 45 days away. Still, hurdles for the $4.5 billion project remain, including the installation and testing of elevators and escalators at its 72nd and 86th street stations, according to an update presented to the MTA on Monday.

Prendergast elaborated that the agency had originally aimed vaguely to launch the line “in 2016.” That commitment has been pushed to the brink.

“It just so happens that the last day of 2016 is Dec. 31,” Prendergast said matter-of-factly. “I don’t know if they honestly thought about the fact that it was New Year’s Eve. A lot of people in the world watch the ball drop … So it provides another set of challenges for us to meet.”

Nick Sifuentes, deputy director of the transit advocacy group Riders Alliance, stressed that it’s important that the line opens without issues.

“I think the MTA is learning lessons from Hudson Yards, which opened up with leaks,” said Sifuentes.

“The most important thing,” he continued, “is for the MTA to open Second Avenue when all the tests are done and everything is in place—not only proving infrastructure projects can get done when we say they’ll be done, but done correctly too.”

Whatever date is chosen, Prendergast said the agency would continue to work “hand in glove” with the police department for the launch.