The Dallas Area Rapid Transit board on Tuesday approved a $976 million budget for 2017 that includes funding for two projects that have led to a clash between Dallas and its neighbors.

DART allotted $3.5 million to a proposed second rail line in downtown Dallas, known as D2, and $25 million to the Cotton Belt rail corridor that would connect DFW International Airport to Plano. But agency officials said DART won't spend any of that preliminary funding until the board approves a 20-year financial plan on Oct. 25 that defines the scope of the projects and funding priorities.

That plan was also supposed to go to a vote Tuesday. But Dallas city leaders asked DART to defer a decision until next month. Members of the Dallas City Council are pushing for D2 to be built as a subway — an option twice as costly as a street-level version — and worry that debt tied to the Cotton Belt will threaten federal grants for the downtown rail.

Meanwhile, Addison and Richardson officials said they have been waiting three decades for the Cotton Belt, whose opening had been pushed back to 2035. Now DART is aiming to debut the line by 2022.

"We're playing catch-up already," Richardson Mayor Paul Voelker told the DART board. Dozens of Cotton Belt supporters, including the Addison City Council, showed up at the board meeting Tuesday in yellow shirts that said "Connect North Texas."

DART officials have said they can afford to do both projects at the same time if federal authorities disburse $650 million in grants for D2. Both the subway and the Cotton Belt would cost more than $1 billion each.

The agency's board will review five financial scenarios involving the projects at a public meeting Oct. 4.

The 2017 budget approved Tuesday also includes $25 million for property and engineering work to lengthen Red and Blue Line stations so they can accommodate three cars per train.