The $2.4 billion Revel Casino Hotel, whose opening two years ago on the Atlantic City boardwalk was hailed as a revival of the city’s gambling industry, filed for protection from creditors in federal bankruptcy court on Thursday as the owner formally put the property on the auction block.

The casino’s owner, Revel Entertainment Group, also said it had obtained a $125 million loan to keep the resort open while it seeks a new owner. But it notified the casino’s 3,140 employees that Revel could close as soon as Aug. 18 if efforts to sell the property failed. Analysts say the property is now worth substantially less than $300 million.

Revel’s announcement is a blow to Gov. Chris Christie’s five-year plan to resuscitate New Jersey’s gambling industry. In 2011, the state invested $260 million in the long-stalled casino project so that construction could resume.

Revel’s chief executive, Scott Kreeger, issued a statement on Thursday saying, “We will work to reach an agreement with a new owner who will help ensure Revel’s long-term financial stability and who shares our commitment to providing Revel’s guests and players an exceptional experience in lodging, gaming, entertainment and recreation.”

The company said it filed for bankruptcy protection, which it did on Thursday for the second time in two years, “to address liquidity issues and facilitate a sale of substantially all of Revel’s assets.”

Revel Entertainment, which has lost more than $260 million since the casino opened, began exploring a sale or partnership a year ago. Negotiations with one suitor, Hard Rock International, collapsed in the spring.

“It’s not surprising,” said Alan Woinski, who publishes Gaming Industry Weekly Report. “You can’t keep losing money like they are.”

Revel, whose 57-story hotel is the tallest building in Atlantic City, was supposed to symbolize a new approach to gambling, with an emphasis on luxury, with windows that, unlike other casinos, faced the ocean. The casino itself was on the third floor.

But the resort never took off.

“It was supposed to be like City Center in Las Vegas, not dependent on gambling,” Mr. Woinski said. “But this is a day-tripper market. It’s empty during the week.”

Combined revenues for Atlantic City’s 12 casinos continued to slide. The Atlantic Club, also on the boardwalk, closed in January.

Competition also has sharpened as casinos and slot parlors have opened in Delaware, Maryland, New York and Pennsylvania. Last year, gambling revenues in New Jersey fell to $3 billion, down 41 percent since peaking in 2006 at $5.2 billion.

Revel itself has a star-crossed history. Morgan Stanley, the resort’s principal owner, halted construction in April 2010, walking away from a $1 billion investment. Work resumed under a new ownership group, which included Chatham Asset Management, a hedge fund, two years later with assistance from the state.