Trump Taj Mahal, the Atlantic City casino-hotel Donald Trump once suggested was proof of his deal-making mastery, closed for good on Monday, putting 3,000 people out of work and further eroding the Republican's message that he is an unmatched business success.

The casino closed at 6 a.m. Monday, just hours after Trump faced off with Hillary Clinton during the second presidential debate.

The casino's owner, billionaire investor Carl Icahn, blamed the closure on a bitter disagreement with the casino's unionized workers, who went on strike in July.

When Trump opened the 42-story tower in 1990, he called the project "the eighth wonder of the world." But its financial struggles led Trump's gambling and real estate empire into its first of six corporate bankruptcies.

Besides the name, Trump has had little involvement in the casino for years. Icahn, who helped Trump keep control of the debt-plagued casino in the early 1990s, paid to take over the casino following its parent company's bankruptcy in 2014.

In a statement Monday, Icahn said the casino had lost "almost $350 million over just a few short years" and could not be saved.

"It was simply impossible to find a workable path forward that would not have required funding additional investments and losses in excess of $100 million over the next year," Icahn said. "Like many of the employees at the Taj Mahal, I wish things had turned out differently."

Trump's campaign did not respond to requests for comment Monday. But Trump, who has repeatedly touted his job-creation skills as credentials for the Oval Office, said recently that he was surprised Icahn couldn't keep the Taj Mahal open.

"I felt they should have been able to make a deal," Trump told the Associated Press earlier this month. "It's hard to believe they weren't able to make a deal."

Disagreements between management and the union representing Atlantic City casino workers, Unite Here Local 54, came to a head July 1, when nearly a thousand cooks, housekeepers, bellmen and servers walked off the job after failing to agree on wage and benefit provisions.

After the closure, union president Bob McDevitt issued a statement saying Icahn "would rather burn the Trump Taj Mahal down just so he can control the ashes."

"For a few million bucks he could have had labor peace and a content workforce," McDevitt said. "But instead he'd rather slam the door shut on these long-term workers just to punish them and attempt to break their strike."

Once a rare haven for gamblers outside of Las Vegas, Atlantic City's casino business has been in decline for years due to the rapid legalization of casinos in states such as Pennsylvania, Maryland and New York. The Taj is the sixth Atlantic City casino to close in the last decade.

The Taj was Trump's third Atlantic City casino, following Trump Plaza and Trump's Castle, and it was his grandest, with 1,250 rooms. When it opened, in 1990, it was the largest casino-hotel in the world, and stars such as Michael Jackson and Elle Macpherson were on-site to toast the casino's grand opening.

But its financial troubles began early. When the Taj opened, gaming analysts were already warning that Atlantic City was in distress. The market for casino gambling was cooling, and the Taj was expected to only cannibalize other casinos' business, without bringing new players of its own.

To cover the project, Trump broke his vow to New Jersey regulators and financed the Taj project with $675 million in risky, high-interest junk bonds.

Those loans contributed to the more than $3 billion in debt that led to the near-collapse of Trump's gambling empire. The Taj filed bankruptcy in 1991, roughly a year after it first opened. The Plaza and Castle went bankrupt the next year. As part of his settlement with lenders, Trump agreed to give up nearly half of his equity stakes in the casinos.

Trump's Taj debts were a key obstacle during his negotiations with bankers and bondholders, and as part of the settlements, he was forced to sell his plane and mega-yacht.