Mayor John DeStefano Jr. sounded yet another alarm about the city’s financial troubles today.

The city budget has structural problems and relies on many revenue assumptions that may well fail to materialize, DeStefano said at a press conference at City Hall. In a familiar refrain, DeStefano argued for the need to confront the unsustainable cost of city employee benefits and pensions rather than seek more revenue from one-time sources or increased property taxes.

“We’re adults and we should be doing what a lot of families are doing,” DeStefano said. “This city, which has the fastest growing population in the region, has too much good stuff going on for us to turn on ourselves.”

For the second time in DeStefano’s 18 years as mayor, the city budget will be ending the fiscal year in the red. While the city spent $4.7 million less than it budgeted last year, an $8.9 million shortfall in revenue led to $4.2 million deficit.

In the next fiscal year, several revenue sources included in DeStefano’s proposed budget are on shaky ground at best.

The city expected to sell the Temple Medical Garage for $9 million, but the highest bidder offered just $2.5 million. $2.6 million in revenue is projected from the city’s proposed stormwater authority—which would bill property owners for their storm runoff—but the Board of Aldermen does not seem likely to approve the it. $7 million in savings from privatizing school custodial services hinges upon a state arbitrator’s approval.

The most significant worry, DeStefano said, is whether or not Gov. Dannel Malloy will succeed in obtaining $1 billion in concessions from state labor unions. If he does not, the state will likely curb the flow of money to the city’s budget, a consequence DeStefano said would be “devastating.”

Asked by a reporter whether he expected Malloy to succeed in getting the concessions, DeStefano shrugged: “I have no clue, man.”