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.