FACTBOX: Clinton's proposals to lift gasoline tax

(Reuters) - Democratic U.S. presidential candidate Hillary Clinton has proposed suspending a gasoline tax for consumers over the summer and replacing it with a tax on the "windfall profits" of oil companies.

Rival Barack Obama, a senator from Illinois, has criticized the New York senator's proposal, calling it political pandering that would not save consumers much money.

Arizona Sen. John McCain, the Republican presidential candidate, backs a temporary lifting of the gasoline tax but does not want to tax bulging oil company profits to pay for it.

Below are elements of Clinton's plan as outlined by her campaign:

DRIVER SAVINGS

Clinton says lifting the gas tax would save average drivers some $70 each over the summer, from roughly Memorial Day until Labor Day, or May 26 to September 1, her staff said.

Truck drivers would save some $2 billion total over that time period, Clinton says.

Obama has estimated the savings at roughly $30 per average driver over the summer.

HOW THE WINDFALL TAX WOULD WORK

Clinton's proposal, introduced as legislation, would force big oil companies to pay a 50 percent tax on 2008 corporate profits above a baseline established using an average of profits from 2000-2004.

That money would go into the federal highway trust fund, making up for the gas taxes saved by drivers.

Obama says that funding proposal is unrealistic because President George W. Bush opposes the windfall tax and would almost certainly reject any legislation mandating it. Without revenue from the windfall profits tax, the gas tax holiday would result in less money available for highway, bridge and railroad repairs, Obama says.

PROTECTING CONSUMERS

Obama has said Clinton's proposal would not prevent oil companies from raising gas prices that consumers pay.

Clinton's response: her legislation directs the Federal Trade Commission and the Commodity Futures Trading Commission to use their authorities to ensure that benefits are passed on to consumers and to investigate and prevent price gouging and market manipulation.

WHAT ECONOMISTS SAY