WASHINGTON--Six more senators on Tuesday joined a bipartisan group of 10 senators backing a bill they say will break the stalemate over offshore drilling in Congress.

Three Democrats and three Republicans joined the so-called Gang of 10, making it the Gang of 16. The group supports a bill that would lift a ban on oil and natural gas drilling in the eastern Gulf of Mexico and off the southeastern U.S. coast, invest $20 billion in the development of petroleum-free motor vehicles and extend tax credits for renewable energy.

Among the new converts are two Republican senators facing tough re-election bids this fall, underscoring the role high energy prices are playing on the campaign trail. By signing on with the group, Sens. Norm Coleman of Minnesota and John Sununu of New Hampshire have broken with the majority of their party, which like President Bush, would like to see the moratorium on drilling lifted along the entire Atlantic and Pacific coasts.

Sununu said Tuesday that while he favors lifting the moratorium entirely, the bipartisan bill opens up new areas and has a chance of being passed this year.