Poised to start construction on a $1.7 billion casino this spring, Wynn President Robert DeSalvio said at a press conference on Wednesday, the groundbreaking will be postponed indefinitely due to an administrative appeal filed with the state by Somerville.

The 16-page claim was filed with the state’s Executive Office of Energy and Environmental Affairs, which granted a key environmental permit for the casino in January. After which time, an administrative hearing was demanded by the city to challenge the decision. The legal validity of the permit was challenged by city attorneys and Somerville’s mayor, Joseph Curtatone, in the claim, which cites state regulations that restrict the type of waterfront developments permitted.

The delay, announced at the Wynn press conference attended by two mayors and dozens of labor groups who support the casino, dials up the pressure on Mayor Joseph Curtatone of Somerville. Curtatone, who has been an unwavering opponent of the planned 24-story casino and hotel complex a short distance from Somerville, has emerged as the last major holdout, escalating the high-stakes feud, according to the Boston Globe.

Standing on the planned casino’s site on the banks of the Mystic River, officials from Wynn emphasized the cost of the delay, not only to the casino, but to potential employees of the casino. They warned that the construction’s start could be delayed by a minimum of six months, however, portrayed the project as a done deal. DeSalvio, Wynn’s top executive on the project, assured they weren’t going anywhere and that the casino will be built.

Shortly after Wynn’s press conference, Somerville threw one together of its own where Curtatone vowed to sustain the fight against the casino for as long as necessary. He scoffed at the idea that Wynn would be surprised by last week’s filing and described it as standard procedure for a project of such magnitude. He said he fully expects for Wynn to throw everything at him including the kitchen sink, by way of lobbyists, lawyers and consultants, but that it’s nothing he can’t handle.

Four thousand workers set to work on the project will be affected by the delay as well as the same amount expected to be hired when the complex opens, which according to DeSalvio, is now anticipated to be no sooner than late 2018. The laying of the foundation cannot begin on the site until the appeal has run its course, according to Wynn representatives.

Last month when a deal was struck between Boston officials and Wynn Resorts, the casino’s arduous road to approval finally seemed clear, but then the February 11 appeal happened. Curtatone said that despite insistent appeals from Wynn, he challenged the permit to offset the environmental impact the development would have on the surrounding area. In the appeal, Curtatone contends that the project is too large and that too much traffic would be drawn into the waterfront area by the casino to qualify for the environmental permit. He also states in the claim that the exhaust from the estimated 18,000 automobiles would cause health risks for residents living nearby.