Sen. Benjamin Cardin is pushing for an end of $4 billion a year in subsidies and tax breaks for the five biggest oil companies.
Maryland Attorney General Doug Gansler will join Cardin on Monday at a news conference in Baltimore.
The Democratic senator is backing legislation that would end subsidies for Exxon Mobil, Shell, Chevron, BP and Conoco Phillips. Cardin says the savings from ending the tax breaks would be used for deficit reduction.
Cardin also has sent a letter to the heads of the five companies, urging them to reject any more taxpayer subsidies.