When the House votes — possibly as soon as today — on a bill potentially opening up both coasts to offshore oil drilling, Democratic leaders won’t be worried about getting enough votes. Instead, they will be nervously watching the scoreboard on the Republican alternative.

Democrats whipped Members last week and over the weekend not just to support the compromise-drilling package crafted by Speaker Nancy Pelosi (D-Calif.) — but also to vote against the GOP proposal.

Pelosi has repeatedly blocked the GOP from getting such a vote, but without offering her Caucus a drilling bill of her own, she was almost certainly going to lose.

To get the votes for her package, she leaned on liberal Members to back a bill that includes drilling they oppose, but also initiatives supported by the environmental community, including a 15 percent renewable electricity mandate.

Her job is made easier because the offshore drilling ban, which President Bush opposes, will disappear on Sept. 30. That allows Pelosi to argue that the choice is between drilling as close as three miles off the coast — which the moratorium prevents — or no closer than 50 miles from shore, which is the Speaker’s proposal. Democrats also expect as many as 20 vulnerable Republicans will vote for her bill.

To win a vote against the GOP alternative, she has been whipping dozens of her more moderate Members who have signed on to broader pro-drilling bills and have been getting an earful from constituents back home.

Pelosi reached out to key drilling proponents, including Reps. Gene Green (D-Texas) and Neil Abercrombie (D-Hawaii), and brought them into the negotiations in hopes of keeping them in the fold.

In order to get their support, she had to give up a great deal, with her bill potentially opening up vast new areas of ocean to drilling.

“The oil patch got a lot,” said Rep. Lois Capps (D-Calif.), who was upset with the package but will probably vote for it anyway. “This is what the oil companies wanted. What happened to protecting offshore?”

House Rules Chairwoman Louise Slaughter (D-N.Y.) said last week that Republicans will likely only get one motion to recommit — essentially their only chance to force changes to the bill.

Still, Democrats chafed at the possibility of Republicans hijacking Pelosi’s carefully whipped strategy.

“I don’t know how you support our bill and then support the motion to recommit. If they want ‘all of the above’ they vote for our bill,” Rep. Bart Stupak (D-Mich.) said.

Added Rep. Henry Waxman (D-Calif.): “It would be absurd for us to go forward with a bill and then have the motion to recommit rewrite it with Democratic votes.”

With only one chance to rewrite the bill, the GOP could offer up its own comprehensive energy package, which doesn’t include mandates that utilities use renewable energy but does include investments in renewables, as well as drilling in the Arctic National Wildlife Refuge and revenue sharing with states.

Or Republicans could offer a targeted amendment that would be much harder for Democrats to oppose, such as allowing revenue sharing with states, although they would have to find a small amount of offsets to comply with budget rules.

They could also choose a bipartisan bill authored by Abercrombie and Rep. John Peterson (R-Pa.) that already has dozens of Democratic co-sponsors.

If Republicans offer their broader bill, they could lose a few of their own Members because it includes drilling in ANWR, which the Republican presidential nominee, Sen. John McCain (Ariz.), opposes. The Abercrombie-Peterson bill leaves out ANWR.

Republicans have succeeded numerous times in passing motions to recommit, but this bill has been whipped as heavily as any all year.

Failure to support the Speaker would be a huge embarrassment for Democrats on such a high-profile measure with the elections just a month away.

Abercrombie is “still on board” with the Speaker’s plan, his spokesman David Helfert said Monday.

“Fundamentally a bill is better than no bill,” he said. “It’s still a major step toward energy independence.”

But he said Abercrombie is hopeful that revenue sharing for states and renewable energy programs could be added either later by the Senate or in future years, and he questions the Congressional Budget Office’s scoring of the revenue sharing for new drilling as a loss under pay-as-you-go rules.

Democrats, meanwhile, on Monday outlined an $18 billion tax package that is part of the plan that shifts tax breaks from oil companies to renewables and adds support for natural gas vehicles — a priority of oilman T. Boone Pickens and Democratic Caucus Chairman Rahm Emanuel (Ill.) — to earlier proposals.

But the final package had not yet been released as of press time Monday. As tweaks were being made late in the day to win votes, Democrats had not yet decided whether their bill would be ready for a vote today.