As negotiators begin work on a surface transportation bill this week, the House Republican freshman class is yet again likely to be the wild card in determining whether the two sides can strike a deal.

Even though Democrats and Republicans successfully negotiated an extension of the payroll tax cut and jobless benefits earlier this year, more uncertainty looms over the conference committee this time around. Aides in leadership and close to the panel had difficulty gaming out what a final agreement might look like or how the conferees will get there because of the dynamics of the panel. Eight of the 20 conferees appointed by Speaker John Boehner (Ohio) are freshmen, and sources say how they swing will be crucial to how the process works out.

If the conservative newcomers are willing to give some ground to reach a compromise with Senate Democrats, the gamble to stack the panel with them could reward Boehner by making it easier to sell the deal to the rest of his Conference.

“It’s good to have those people invested in the process,” one Democratic leadership aide said of the GOP freshmen. “The million-dollar question will be: Will they be productive negotiators?”

The aide conceded that their presence on the committee could be a blessing or a curse. If the freshman Members try to swing the final product too far to the right, Democratic Senators — who largely feel they have the upper hand in negotiations — could balk. Indeed, the Senate is the only chamber that has passed a comprehensive measure; a two-year transportation and infrastructure bill passed on a broad, bipartisan 74-22 vote. Both co-sponsors, Environment and Public Works Chairman Barbara Boxer (D-Calif.) and ranking member James Inhofe (R-Okla.) are conferees. House Republicans are working off a bill that leaders declined to bring to the floor because of a lack of GOP rank-and-file support.

Given the Senate GOP’s support for that chamber’s measure, House Republicans could find themselves holding a lonely vigil for a more conservative product. Still, House GOP conferees will hold plenty of sway. Their approval would make final House passage of a compromise much less complicated, House aides say. And Democrats know it, too.

“If they sign their name, they tend to bring people along with them,” the Democratic aide said.

The full conference committee will hold its first formal meeting on Tuesday afternoon. Staff met for an informational and organizational meeting last Wednesday. Before last week’s recess, Republicans on the House Transportation and Infrastructure Committee met among themselves, as did the entire slate of Democratic conferees.

The Senate legislation includes some modest reforms to the transportation and infrastructure system while authorizing projects both sides have touted as jobs-creating. The House measure is a temporary extension of current law that includes language attempting to force action on the Keystone XL oil pipeline. Boehner’s original draft bill was a five-year measure that would have more seriously reformed the system but cut more project funding.

GOP aides pointed to programmatic reform as a place where negotiators might be able to find compromise. The House legislation reorganized and consolidated about 100 programs within the four major relevant agencies — the Federal Transit Administration, Federal Motor Carrier Safety Association, National Highway Traffic Safety Administration and Federal Highway Administration — into 35 programs. The Senate bill does some of this consolidating, but not as significantly. House sources believe the Senate bill is a start but that the negotiators could do better.

Some of the largest points of contention will likely be the inclusion of the Keystone pipeline and earmark rescission.

The pipeline has become part of nearly every major policy debate this year, with Republicans pressing for its authorization and touting it as important for the economy and the White House repeatedly threatening to veto any bill that includes it.

The composition of the conference is assuredly Keystone-friendly, with bipartisan Senate advocates such as Finance Chairman Max Baucus (D-Mont.) and Sen. John Hoeven (R-N.D.). But the panel also includes top Senate Democrats Charles Schumer (N.Y.) and Dick Durbin (Ill.), who will likely take the side of Majority Leader Harry Reid (Nev.), who has pushed back against the pipeline.

But regardless of how intense talks might get inside the negotiating room, don’t expect too many press events outside it, according to sources. No one wants to poison the well too soon as both parties try to navigate toward a deal.

But even promises of civility aren’t likely to keep leaders from subtly digging each other to get things done.

In a statement released Friday about the most recent jobs report, for example, Reid called on House Republicans to help pass the bill.

“Creating jobs must remain Congress’ top priority,” Reid said. “Unfortunately … the House is sitting on bipartisan bills to save three million transportation jobs, and modernize the postal industry. There is no reason why we should not pass these common-sense jobs bills without delay — no reason except for Republican obstruction.”