The growing number of senators who support the plan puts pressure on leaders from both parties — and their presidential candidates — to advance a version of the energy compromise in the final weeks of the congressional session. And it seems likely to win support from Sen. Barack Obama (D-Ill.), allowing him to deflect GOP attacks that he opposes more oil drilling. But it has drawn criticism from the environmental community, which says new drilling would do little to reduce gas prices while harming pristine coastlines.

The added support comes as House Republicans have been protesting Speaker Nancy Pelosi’s (D-Calif.) decision to adjourn the chamber for the August recess without a vote on offshore drilling.

The Senate proposal now has drawn support from eight members of each party. It was initially drafted by 10 senators who are modeling their efforts after the "Gang of 14" in 2005, which reached a bipartisan accord to avert a partisan meltdown in the Senate over judicial nominees.

“Support for a balanced, bipartisan approach to increase our country’s energy security is growing, and I believe this momentum clearly shows that the way forward on energy is a meaningful approach that enables our country to produce more energy here at home and use less as we move to alternative energy sources,” said Sen. Bob Corker (R-Tenn.), an original member of the group.