HARRISBURG - Call it the Big Sell.

In the hours leading up to what is widely expected to be a historic vote Thursday on whether to privatize alcohol sales in Pennsylvania, activity has intensified behind the scenes as much has it has on the House floor.

Lobbying in the hallways. Phone calls from the governor. A frantic numbers game - are the votes there? Whose mind needs changing, whose arm needs twisting just a bit harder?

Such a frenzy of lobbying hasn't been seen in the Capitol on a single issue - other than the annual budget - since Gov. Ed Rendell's days.

The policy stakes are high. Gov. Corbett, a Republican, has called for auctioning off the State Stores and directing the proceeds to public schools.

The political stakes are high, too. Strategists say Corbett needs a legislative win to bolster his sagging approval ratings. Several House Republicans tell of a blunt warning recently received: If privatization fails, they could be calling Democrat Allyson Y. Schwartz "governor-elect" come fall of 2014.

Exaggeration or not, this much is clear: The governor has stepped out of his comfort zone and thrown himself, and much of his political capital, into getting liquor privatization through the Assembly. And the House is the first battleground.

Not one to aggressively target legislators in the past, the governor has switched gears and has been personally calling members of the House's GOP majority who are key to the privatization bill's chances. (Democrats in the House appear solidly opposed, with no cracks apparent in their ranks.) The governor's top-level staff has also been summoning to closed-door meetings any GOP legislators who admit being undecided.

And in the last few days, Corbett himself has been spotted at downtown restaurants, making the rounds at campaign fund-raisers for House Republicans who aren't even up for reelection this year. At each stop, according to those attending, he has engaged in small talk - and made a pitch for privatization, as has Lt. Gov. Jim Cawley, his point man on the issue.

Then there is Majority Leader Mike Turzai (R., Allegheny), privatization's most vocal supporter in the legislature. He has spent much of the last week shoring up votes in his caucus and making new lists of who is on board and who is not.

Other top Republicans have been pounding their undecided colleagues with this message: Corbett needs this, or his reelection campaign next year will be in jeopardy.

The alternative, those Republicans have noted, is a Democrat in the governor's mansion. U.S. Rep. Schwartz's name has been thrown around, even though the liberal Democrat from the Philadelphia suburbs has not yet announced her much-anticipated run for governor.

"That point has been made over and over again, and is widely understood," said a top Republican who did not want to be named. "Do you want Tom Corbett in the governor's office, or do you want a Democrat?"

Political analyst G. Terry Madonna agreed that Corbett badly needs a victory. And getting one on liquor privatization - a Sisyphean goal that has eluded previous Republican governors - could go a long way toward showing he has the mettle to push through a bold agenda.

"I think Republicans are maybe becoming more realistic about it," Madonna said. "Leaders who may not favor it, especially in the Senate, understand that it may not be in their interest to see him lose this fight."

Democrats understand that dynamic, too, and for the moment seem unified against privatization.

Wendell Young IV, president of Local 1776 of the United Food and Commercial Workers, said the bill's fate hinges on about 15 House members whom he described as being pressured "until they bleed."

The head of a union that represents about 3,500 clerks at the 600-plus State Stores, Young - who is lobbying hard against privatization - said legislative leaders typically cajole by promising to bring up a member's favorite bill for a vote - or coerce by threatening everything from having committee assignments yanked to office spaces changed.

Both sides are working the electorate, too. The AFL-CIO has called union households, urging them to contact legislators and ask for a "no" vote. Corbett, in his most recent newsletter, asked the same of citizens - but to push for an "aye" vote. And the conservative Citizens Alliance of Pennsylvania wrote to legislators Wednesday warning that they could face challenges in next year's primary if they voted "no," the online news service Capitolwire reported.

Which lawmakers are being pressured most? Young wouldn't name names. But Corbett and others have zeroed in on Bucks County Republicans.

Historically, this group has sat on the fence in fights over liquor privatization. In a chamber of 111 Republicans and 90 Democrats (plus two vacancies), Bucks County boasts seven GOP legislators. Some are social conservatives, such as Rep. Paul Clymer, who favors keeping liquor tightly controlled, and are reliable "no" votes. But in the quest for the 102 "ayes" needed for passage, the Bucks County undecideds, as they have come to be called, have become prime targets for both sides.

They have heard from beer distributors - such as Bucks GOP heavyweight Pasquale T. Deon, who is also on the SEPTA board and the Pennsylvania Turnpike Commission. Deon could not be reached for comment Wednesday.

One of the undecideds is Rep. Scott Petri (R., Bucks), who has concerns about the bill. Chief among them: the impact on small and family owned beer outlets. "If this debate is about what the consumer wants, I'm not sure this bill gets us there," he said in an interview.

As for being lobbied, "I've heard from everyone, from people inside the Capitol, from people in my community," Petri said. "It really hasn't stopped."

Contact Angela Couloumbis at 717-787-5934 or acouloumbis@phillynews.com.