The U.S. Chamber of Commerce said Wednesday it will attempt to do what a string of economists and urban planners couldn't: convince lawmakers and the public to raise the federal gasoline tax to pay for better roads.

The new push by the powerful business lobby, which includes a six-figure ad campaign, comes as Congress has begun debating how to pay for a growing list of needed repairs to the nation's highways, bridges and mass-transit systems. Boosting the 18.4-cent federal tax on a gallon of gasoline by roughly 10 cents a gallon would cover the growing funding gap while creating jobs and improving mobility, Chamber officials said Wednesday.

"Just damn do it," Chamber President Thomas Donohue said Wednesday at a press briefing, at which he called on Congress not to delay action on a new highway bill - as the Obama Administration has proposed. Wednesday, the Senate Energy and Public Works Committee backed a plan to put off debate over new highway funding for 18 months, extending current funding levels until then.

A boost in highway spending could also be a boon for Chamber members like Caterpillar Inc. (CAT), the heavy-equipment maker that has joined the lobbying campaign.

About 100 business executives affiliated with the Chamber fanned out on Capitol Hill Wednesday to meet with lawmakers. The executives ranged from small retailers from North Myrtle Beach, S.C., to Office Depot Inc. (ODP) Chief Executive Steve Odland.

While the Chamber has previously called for a gas-tax increase, the group is ramping up lobbying because now is an opportune time to make such a move, with gas prices well below last summer's peak of $4 a gallon, Donohue said.

The Chamber has begun paying for billboards in various states and ads in Capitol Hill newspapers advocating a boost in transportation spending.

The gas tax hasn't been raised since 1993, and an increase is seen as a risky political move that would invite a public backlash, particularly during a recession. Transportation Secretary Ray LaHood repeated in a congressional hearing this week that the administration wouldn't raise the gas tax during a recession.

But Mr. Donohue said the chamber will try to assure officials that businesses will support such a move, providing cover for lawmakers.

"We certainly want to negate this issue of a gas tax as a campaign issue," said Janet Kavinoky, a transportation lobbyist for the U.S. Chamber. "When these members go home, they've got to hear from their constituents, 'This is OK.'"

She said that while many lawmakers are still expressing fears that they would draw voters' ire by voting for a gas-tax increase, she has seen "cracks in the armor," with some expressing more openness to a fuel-tax increase, at least in the mid-term.

Sen. Barbara Boxer, D-Calif., chairwoman of the Environment and Public Works Committee, said during a hearing last month that she opposed an immediate gas-tax increase but would be open to eventually tying fuel-tax increases to inflation.

Office Depot's Mr. Odland said the idea that Congress is unwilling to raise taxes is "laughable." He cited climate-change legislation that would force businesses to purchase permits for greenhouse-gas emissions, and a proposed surtax on the wealthiest Americans to pay for health-care coverage.

"We're raising taxes all over the place," Mr. Odland told reporters Wednesday, saying gas taxes should be considered "user fees" on drivers and businesses. "Stop with those taxes and let's start with the user fees."

The Chamber is supporting legislation by Rep. James Oberstar, D-Minn., chairman of the House Transportation Committee, to spend $500 billion over six years on transportation projects - a 40% increase over current spending.

Jim Berard, a spokesman for Mr. Oberstar, said the Chamber's lobbying campaign is "welcome" as a way to gather support for increased funding, but that a short-term spike in the gas tax is unlikely.

"The political environment here in Washington and nationwide would appear to be opposed to any increase" in the fuel tax, Mr. Berard said.

"The economic reality is that people are out of jobs, money is tight, the economy is stagnant. So a tax directly to the consumer of any size would most likely not be welcome."

-By Josh Mitchell, Dow Jones Newswires; 202-862-6637; joshua.mitchell@dowjones.com