When lawmakers return to Washington after their holiday hiatus, they won’t be greeted with a slate swept clean by the New Year. Instead, they’ll be picking up right where they left off in the complicated and expensive battle over just how to repair failed negotiations to extend the payroll-tax cut as well as a smorgasbord of tax breaks.

Although the two-month extension on the payroll-tax cut led to the creation of a conference committee to negotiate a deal on it, the familiar battleground is still littered with unfinished business from last year.

One of the casualties of those failed talks was a package of miscellaneous tax breaks and benefits that were set to expire at the end of last year. Extending those 71 tax measures would have required as much as $300 billion in cost offsets — a sum well beyond the common ground lawmakers were able to find in the 11th hour of 2011.

Lawmakers and staffers in both the House and the Senate acknowledge that the extension of the popular and widely used tax breaks must be handled this year, but there remains no consensus on how exactly that should be done. Republicans in the House took the tax-break extenders off the table to smooth the way for a long-term payroll tax extension. At the time, Rep. Charles Boustany, R-La., told National Journal that, while the situation wasn’ t ideal, the plan was to handle the popular provisions early in 2012 to allow businesses and individuals to adjust.

“They would have to be retroactive,” he said. “You have a little bit of leeway if you do it early enough in the first quarter.”

But that was when lawmakers expected that the payroll-tax problem would be out of their hands for at least another year. Now GOP leaders are faced with the same problem as before: How do you sell a multibillion-dollar tax package to a frustrated caucus of deficit hawks?

But it is unclear if Republicans can be convinced to go along with using the payroll-tax package as the vehicle for the tax-break extenders. The members negotiating on the conference committee have not yet formally convened to decide the next steps. There remains some question about just when the extenders even need to be done.

“While there is precedent for doing extenders in the calendar year they are set to expire, there is also a similar precedent to take them up retroactively,'' said one House GOP aide.

But Democrats are expected to use the conference committee to push for an early resolution. Last year, Senate Majority Leader Harry Reid, D-Nev., and Sen. Max Baucus, D-Mont., the chairman of the Senate Finance Committee, both told reporters that the extenders were a key element of their negotiations for the payroll-tax extension.

Now Senate Democrats will have the opportunity to capitalize on the popular perception that Republicans mishandled the extension last year. And they will be joined by an equally emboldened group of House Democrats looking to regain control of their message after a dismal year in the minority.

Democrats -- including conference committee appointee Rep. Sander Levin, D-Mich., the top Democrat on the House Ways and Means Committee -- have already begun to press Republicans on more than just the payroll-tax extension.

“Tax extenders include a number of important provisions, such as the research and development credit that supports job creation, and the House Republican majority needs to act on them in the coming weeks so businesses have the certainty they need this year,” Levin said.

But that is a heavy lift for a conference committee that will have fewer than six weeks to reach a deal. Negotiators are expected to meet early next week, but details remain elusive, despite the ticking clock.