Heads of the five biggest oil firms in the US have been defending the tax breaks their industry gets amid criticism from some politicians."Our industry and company are already taxed heavily," said ConocoPhillips chief executive James Mulva, appearing before the Senate finance committee.
Committee Democrats want to pass legislation repealing the breaks.
They say it would save government $1.2bn by 2012 and only dent oil industry profits in 2010 by $76bn.
'Un-American' "Businesses should make a profit - that's what drives our economy," said committee chairman Max Baucus. "But do these very profitable companies actually need taxpayer subsidies?"
A fellow Democrat, Ron Wyden, played back recordings of previous hearings in 2005 in which oil executives said they did not need subsidies, at a time when the oil price was nearly half what it is now.
"You all said you didn't need them in 2005. You seem to be telling a different story today," said Mr Wyden, addressing the heads of Shell, Exxon, Conoco, BP America and Chevron.
Chevron's boss, John Watson, complained that oil firms only benefited from the same tax breaks as any other US industry.
Another Democrat committee member - Robert Menendez - has written draft legislation that prevents oil companies from taking advantage of a tax deduction meant to help manufacturers, as well as stopping them from deducting foreign royalties from their US tax bill.
Mr Menendez asked the Conoco chief executive to apologise for a press release that described the tax changes as "un-American", but Mr Mulva declined, saying that no personal offence was meant by the statement.
Democrats will be hard pressed to push the bill through the Republican-controlled House of Representatives, and even in the upper chamber, some Democratic senators have come out against the legislation.
"All this hearing is about is providing justification for tax increases," said Republican Senator Orrin Hatch, who also sits on the committee.