Raising the federal gas tax to pay for transportation funding is "on the table," Transportation Secretary Elaine Chao said Tuesday.

She said raising the tax, which has not been increased in 25 years, is not an ideal solution, but repairing the nation's roads is so important that the Trump administration would consider it.

"The president has not declared anything out of bounds. Everything is on the table," Chao told reporters at the White House when asked if the president would agree to a 25-cent-a-gallon increase proposed by the Chamber of Commerce. She added that the gasoline tax has a "very regressive effect" on low-income Americans and called on Congress to look for better solutions to pay for the Highway Trust Fund.

Chamber of Commerce President Tom Donohue called for an increase of 5 cents per gallon every year over five years in a USA Today op-ed last week. "The modest hike we're proposing would cost the average American only about $9 a month in additional gas taxes. That figure, however, is dwarfed by the cost of inaction," he said.

The tax is currently 18.4 cents for gasoline and 24.4 cents for diesel and goes into the trust fund. The tax has not been raised in 25 years, the last time being during former President Bill Clinton's first year and only after a contentious congressional battle that had Vice President Al Gore casting the deciding vote.

No proposal since then has gained much traction at the federal level. Most Republicans balk at tax increases. Democrats such as Rep. Pete DeFazio, D-Ore., have called for an increase, but many liberals view gas taxes as regressive.

Since 2013, more than 25 states, including right-leaning ones such as Wyoming and Georgia, have raised their gas taxes because of federal inaction.