Lawmakers raced Monday to authorize an expanded mission to arm and train moderate Syrian rebels before heading back to the campaign trail, with President Obama's fiercest opponents in the House GOP preparing to consent -- on condition no U.S. ground forces are deployed in the fight against the Islamic State group.

Approval would allow the Obama administration to implement a central plank of its plan to combat the extremists who've conquered large parts of Iraq and Syria and beheaded two American journalists, underscoring their designation as a top U.S. terrorism threat in the region and beyond. The House and Senate are both on a tight schedule, looking to wrap up work Friday before an almost two-month recess in preparation for November's midterm elections.

The authorization under consideration will likely be included as an amendment to a spending bill Congress must pass to keep the government open until mid-December. That would give lawmakers the opportunity to hold a separate debate and vote on the matter -- something members of both parties want.

House Republicans say authorization will come with an explicit ban on U.S. combat troops in Iraq or Syria, and a demand that the Pentagon present Congress with a plan 15 days before any training begins, according to a House Armed Services Committee aide, who wasn't authorized to speak publicly on the record about ongoing deliberations and demanded anonymity.

Democrats are reviewing the proposal, which would enable the military to take over what has previously been a limited, covert operation to beef up rebels battling extremist groups and President Bashar Assad's army. 

The administration isn't likely to protest the conditions. It has sent more than 1,000 troops to Iraq to provide military assistance and bolster security of U.S. diplomatic facilities and personnel. But Obama, too, opposes any U.S. ground offensive.

The House Rules Committee planned to meet as early as Monday evening and Republicans were to gather for internal talks Tuesday morning. A House vote could be held Thursday with the Senate then following, by which time both chambers will have had opportunities to question the administration's top national security officials.

Defense Secretary Chuck Hagel briefs House and Senate committees Tuesday and Thursday, and Joint Chiefs Chairman Gen. Martin Dempsey also testifying. Secretary of State John Kerry appears before separate panels Wednesday and Thursday.

Obama's approach to fighting the Islamic State group largely sidesteps Congress. The president isn't asking for permission to expand strikes in Iraq and target the militants' operational bases and command structures in Syria, a source of consternation for some Democrats and Republicans who say the Constitution demands the legislative branch declare war.

Rep. Adam Schiff, D-Calif., is introducing a bill providing that authorization while limiting U.S. engagement to 18 months and ruling out military action outside Iraq or Syria. Such legislation isn't likely to get a look until next year, if at all. "It is truly ironic the administration thinks it needs to ask for authorization ... to fund opposition forces, but it can proceed to go to war without Congress," Schiff said in a telephone interview.

In the Senate, Democrat Tim Kaine of Virginia and Republican Bob Corker of Tennessee have led similar efforts.

Obama's opposition to ground forces explains why U.S. officials are attaching such importance to enhancing the capacities of Syria's more moderate rebels. They've received little in military assistance from the United States over three-and-a-half years of civil war and have been overwhelmed by opponents on both sides. Until recently, U.S. officials were among the most opposed to providing them with greater assistance.

The U.S. plan is to develop moderate forces in Saudi Arabia before helping them return to the battlefield. It's unclear how long they will need to be battle ready or how the U.S. can ensure their attention remains on fighting extremists and not just the Syrian government.

Many Republicans and Democrats have expressed reservations about the ability to identify moderates in a country awash with rebel formations and shifting alliances. The Islamic State grew out of the Al Qaeda movement, but the two are now fighting. In some instances, the moderate Free Syrian Army has teamed with Al Qaeda's local franchise, the Nusra Front.

The House's effort would provide lawmakers with information on the vetting process and which groups are being recruited. The administration didn't ask for money to conduct the arming and training mission because it expects foreign donors to fund the program, the House aide said. 

In any case, the Pentagon has billions of dollars in wartime contingency funds it can ask Congress to release.