The average S.C. taxpayer would save about $689 on their state income taxes under Republican Gov. Nikki Haley’s tax-swap plan that would cut state income taxes and increase the gas tax.

Those savings would be offset, to a small degree, by having to pay about $66 on average in higher gas taxes.

But don’t start spending your tax savings yet.

The state’s most powerful politician all but declared Haley’s tax-swap proposal dead Thursday.

State Senate President Pro Tem Hugh Leatherman, R-Florence, said the loss in state income tax revenue —$1.8 billion in 2025 alone — would force huge cuts to other state programs, including education, public safety and mental health.

The Senate leader also said Haley’s proposed gas-tax increase, which would raise about $3 billion over 10 years, is not enough to address the state’s $15 billion deficit in the money it needs to fix roads and bridges over the next decade.

“We’re not raising enough to fix the problem, but yet we’re eroding our tax base, and that erosion is not a one-time erosion, it will be there year after year, after year,” said Leatherman, who also is chairman of the Senate Finance Committee.