In the first session of the 110 th Congress, the House and the Senate passed two markedly different versions of omnibus energy efficiency and renewable energy legislation. The Senate version of H.R. 6 , the proposed Renewable Fuels, Consumer Protection, and Energy Efficiency Act of 2007 , passed the Senate on June 21, 2007. The key provisions of the Senate-passed H.R. 6 are appliance efficiency standards, an increase of the renewable fuel standard (RFS) to 36 billion gallons by 2022, and an increase of the combined corporate average fuel economy (CAFE) standards to 35 miles per gallon (mpg) by 2020. Tax provisions and a renewable energy portfolio standard (RPS) were not included. The House passed H.R. 3221 on August 4, 2007. H.R. 3221 has two divisions. Division A contains the New Direction for Energy Independence, National Security, and Consumer Protection Act , which has nine titles An adopted floor amendment ( H.Amdt. 748 ) added a 15% renewable portfolio standard (RPS). Division B, the Renewable Energy and Energy Conservation Tax Act of 2007 , contains the House-approved version of H.R. 2776 . It adds four titles to H.R. 3221 that include a four-year extension of the renewable electricity production tax credit and other efficiency and renewables incentives. This report compares the major provisions of the House version of H.R. 3221 , and the Senate version of H.R. 6 . (For more details on the provisions in these two bills, see the appendices to this report. For more details on the legislation that led to the omnibus bills, see CRS Report RL33831, Energy Efficiency and Renewable Energy Legislation in the 110 th Congress . For more details on the tax provisions, see CRS Report RL33578, Energy Tax Policy: History and Current Issues .) The following analysts in the CRS Resources, Science, and Industry Division contributed to this report: [author name scrubbed], transmission and electric utilities, [phone number scrubbed] [author name scrubbed], fuel economy standards, [phone number scrubbed] Lynne Corn, wildlife and habitats, [phone number scrubbed] Susan Fletcher, international climate cooperation, [phone number scrubbed] [author name scrubbed], carbon storage, [phone number scrubbed] [author name scrubbed], loan guarantees, [phone number scrubbed] [author name scrubbed], oil and natural gas royalties, [phone number scrubbed] [author name scrubbed], marine energy, [phone number scrubbed] [author name scrubbed], energy taxes, [phone number scrubbed] [author name scrubbed], energy prices, [phone number scrubbed] [author name scrubbed], agriculture-based energy, [phone number scrubbed] Brent Yacobucci, biofuels, [phone number scrubbed] The Senate version of H.R. 6 , the proposed Renewable Fuels, Consumer Protection, and Energy Efficiency Act of 2007 , was derived primarily from S. 1419 , which, in turn, was composed from four major bills: the Energy Savings Act ( S. 1321 ), the Public Buildings Cost Reduction Act ( S. 992 ), the Ten-in-Ten Fuel Economy Act ( S. 357 ), and the Energy Diplomacy and Security Act ( S. 193 ). A summary of the Senate-passed version of H.R. 6 is presented in CRS Report RL33831, Energy Efficiency and Renewable Energy Legislation in the 110 th Congress . That report also contains descriptions of all the bills that composed the Senate version of H.R. 6 . An RPS amendment ( S.Amdt. 1537 ) was introduced during Senate floor action on the proposed substitute ( S.Amdt. 1502 ) to H.R. 6 . The RPS amendment proposed setting a target of 15% by 2020. No action was taken on S.Amdt. 1537 before a successful cloture vote on the substitute. That cloture vote caused S.Amdt. 1537 to be ruled non-germane, and it fell from consideration. A package of tax provisions ( S.Amdt. 1704 ) was considered during Senate floor action on the proposed substitute to H.R. 6 . The proposed tax package amendment included oil and natural gas revenue offset provisions, as well as incentives for renewable energy and energy efficiency. The proposed revenue offsets were similar to, but more extensive than, the offsets proposed in Title XIII, Subtitle A, of H.R. 3221 . However, S.Amdt. 1704 failed by a vote of 57-36 on a cloture motion to limit debate. (For more details, see CRS Report RL33578, Energy Tax Policy: History and Current Issues .) H.R. 3221 has two divisions. Division A contains the New Direction for Energy Independence, National Security, and Consumer Protection Act , which has nine titles that represent the integration of H.R. 364 , H.R. 2304 , H.R. 2313 , H.R. 2337 , H.R. 2389 , H.R. 2420 , H.R. 2635 , H.R. 2701 , H.R. 2773 , H.R. 2774 , H.R. 2847 , and a draft bill by the Committee on Energy and Commerce. Division B, the Renewable Energy and Energy Conservation Tax Act of 2007 , contains the House-approved version of H.R. 2776 , and adds four titles to H.R. 3221 . A summary of the bill is presented in CRS Report RL33831, Energy Efficiency and Renewable Energy Legislation in the 110 th Congress . That report also contains descriptions of all the bills that composed the House-passed version of H.R. 3221 . One challenge involves key differences between the provisions of the two bills. There are several provisions where the two bills are very similar. One example is energy efficiency standards, where the House and Senate provisions have more similarities than differences. However, especially among the more controversial provisions, many either have major differences or the provision appears only in one bill. One key challenge will be to resolve such differences. A second challenge involves additional action that will be required to get a bill to conference committee. Because the House and Senate have passed different measures, constitutionally-required congressional procedures prevent the two bills ( H.R. 3221 and H.R. 6 ) from going to conference in their current form. Further action will be needed on at least one of the two bills in at least one of the two chambers. For example, one option could be that the Senate takes up H.R. 3221 , amends it however it wishes, and then pass the bill as the Senate version of H.R. 3221 . Then, a conference could be held to resolve any remaining differences between the two versions of H.R. 3221 . A third challenge involves opposition to the bills expressed by the Administration. In a June 12, 2007, Statement of Administration Policy on H.R. 6 , the Administration expressed several points of opposition to the Senate bill. Its primary concerns involved issues related to oil and natural gas. The Administration stated that the bill "does nothing to increase domestic supplies of oil and natural gas." Moreover, it threatened to veto the bill if it retained a price gouging provision, which it feels would lead to problematic gasoline price controls. Another veto threat was focused on the proposal to subject foreign oil cartels to the jurisdiction of U.S. courts. Additional concerns were identified. One concern focused on the explicit 35 mpg fuel economy target in the CAFE provision and the proposal to set standards for medium- and heavy-duty trucks. For the RFS provision, the Administration strongly urged expansion to include fossil-based alternative fuels. Regarding loan guarantees, the Administration stated opposition to loosening of controls over program size and "special" treatment that would allow guarantees for biofuels projects to be increased to from 80% to cover up to 100% of project costs. In an August 3, 2007, Statement of Administration Policy on H.R. 2776 and H.R. 3221 , the Administration expressed several points of opposition to the House bill. Its primary concerns were focused on oil and natural gas. It stated that because the two bills "would lead to less domestic oil and gas production, higher energy costs, and higher taxes, the President's senior advisors would recommend that he veto these bills." Other concerns included the proposed repeal of the manufacturing tax deduction for the oil and gas industry, the application of royalty requirements for certain offshore oil and gas leases issued in 1998 and 1999, increased authorization for clean renewable energy bonds, and expansion of the Davis-Bacon prevailing wage requirements. After the House completed action on H.R. 3221 , informal bipartisan negotiations over the omnibus energy bills began between the House and Senate. Key issues seem to include the RPS provision (Title IX, Subtitle H) in the H.R. 3221 , differences over proposals for increasing the renewable fuels standard (RFS), and a proposal to offset costs by repealing certain oil and natural gas subsidies. In November 2007, EIA issued a report on the impacts of the RPS and oil and gas provisions in H.R. 3221 . On December 1, 2007, the Ranking Member of the Senate Committee on Energy and Natural Resources stated that the House Leadership's intent to include an RPS led him to cease negotiations. Further, on December 3, 2007, the White House announced that it may veto the negotiated bill, if it includes an RPS, oil tax increases, and certain other provisions.