CNN

House Democrats are lobbying their counterparts to support a landmark energy bill.

WASHINGTON (CNN) – House Democratic leaders are furiously lobbying their members and moderate Republicans to support a landmark energy bill in the face of resistance from some conservative members of their own party, and staunch opposition from the GOP - roadblocks that are making it difficult to find the 218 votes necessary to pass the measure, according to Democratic leadership aides.

A vote on the Clean Energy and Security Act, which would restrict emissions of green house gases and require use of alternative energy in an effort to slow the effects of global warming, is scheduled for Friday.

The legislation's lead sponsors held a pep rally outside the Capitol on Wednesday to whip up support for the legislation's passage.

"We are going to pass the most important energy and environment bill in history," declared Rep Ed Markey, D-Masachusetts, chairman of the Select Committee on Energy Independence and Global Warming. "We are going to reduce the carbon we send up into the atmosphere but at the same time we are going to begin to back out the oil that we import from countries that we should not be importing it from."

The legislation would require a 17 percent emissions reduction from 2005 levels by 2020, mandate electric utilities to meet 20% of their electricity demand through renewable energy sources by 2020, provide $90 billion for new investments in energy efficiency and renewable energy, along with $60 billion for carbon capture and sequestration. Another key provision, termed "cap-and-trade," would require industries and manufacturers to cut carbon emissions by setting up a system where they could buy and sell pollution credits.

Speaker Nancy Pelosi conceded Wednesday evening that there were not enough votes to pass the bill, but that meetings with Democrats and Republicans were ongoing. Many Democrats from rural districts are concerned about the bill's effect on the manufacturing of ethanol and other biofuels, while Republicans have questioned the overall price tag to Americans.

"This legislation has really been quite an experience for all of us," said Pelosi. "This is really about regional differences, as well as philosophical differences."

Democrats are hoping that a recent evaluation by Congressional Budget Office (CBO), which estimates that the annual economywide cost of the cap-and-trade program in 2020 would be $22 billion - or about $175 per household, is enough to alleviate concerns of some members.

But House Republican leaders claim the CBO estimate is too low, and doesn't adequately gauge the harmful effect that stricter regulations will have on business and industry.

"There is no question that the cap and trade bill will cost millions of jobs and it is pretty evident, I think now, given the word that we are hearing that the other side has 190 votes at this point, far short of that which are needed to pass this bill," said House Minority Whip Eric Cantor, R-Virginia.

Despite concerns about not getting any Republicans to ultimately support the bill, Democratic leaders are hoping their more conservative members coalesce around a "grand agreement" being worked out with Rep Colin Peterson (D-MN), chairman of the Agriculture Committee and a leading voice for rural Democrats concerned with the bill.