Even if the Feb 2 election is held as scheduled and a new government can be formed, the time-consuming process of approving and setting aside a budget will delay the investment, he said.
Moreover, the borrowing bill is pending in the Constitution Court after the Democrat Party asked for a ruling on its constitutionality.
The infrastructure investment, initiated by the Pheu Thai Party-led administration, was previously expected to start by this fiscal year and be the main driver in revitalising the lacklustre economy.
Given potential delays to the investment, 5 billion baht of public debt estimated for this fiscal year will be shaved off, Mr Kittiratt said.
He said the US dollar's strength has hardly had any effect on public debt, as the yen, which is the major foreign currency of Thailand's debt, has weakened against the baht to offset the dollar's appreciation.
The new government may need to set aside an extra budget in fiscal 2014 or borrow from financial institutions to finance investment in priority projects if the borrowing bill is derailed, said Chanvit Amatamatucharti, deputy secretary-general of the National Economic and Social Development Board.
The infrastructure projects could still move ahead as planned through those means even if the borrowing bill aborts.
Amid uncertainty about a global economic recovery and the fragile state of domestic consumption, any new governing political party will likely depend on the 2 trillion baht in infrastructure spending to jump-start the economy.
Time-consuming legal proceedings could delay the borrowing bill for years, as a Constitution Court ruling is not expected until the second half of this year.
The Finance Ministry earlier said it plans to borrow using the Public Debt Management Act to start investment in the infrastructure projects if the borrowing bill is struck down.
Based on government expenditure of 2.525 trillion baht set for fiscal 2014, a new government could seek up to 252.5 billion in borrowing.
Mr Chanvit said each project in the infrastructure plan must obtain cabinet approval and undergo an environmental impact assessment, with or without the borrowing bill.