Even as Senate Democrats line up the votes to pass their $838 billion version of the economic recovery plan Tuesday, the work's not over yet. 

It appears the House and Senate will soon meet in a traditional conference committee to iron out differences between the House version of the stimulus bill and the Senate's package, a session that could last through the weekend. 

The traditional process -- which you may recall from Schoolhouse Rock tutorials -- requires each body to approve its respective version of legislation. 

Then negotiators from both the House and Senate meet to forge a final, unified version to send to the president for his signature. 

Conference committees meet less frequently these days on Capitol Hill. Instead, lawmakers prefer to engage in what is now known on Capitol Hill as "Ping-Pong." 

In other words, the House approves one version of the bill and "pings" it to the Senate. Then the Senate okays its measure and "pongs" it back to the House. The bicameral table tennis continues until both the House and Senate reach a compromise. 

But in this case, House sources indicate that House and Senate negotiators could meet in a conference committee as early as Thursday. 

"We didn't do all of that work to not set a good conference," said House Majority Leader Steny Hoyer, D-Md. 

There are questions, though, about how much room Senate negotiators have to bargain with the House since only three Senate Republicans are planning to vote for the bill. 

"There are obviously differences and we'll have to work these out," Hoyer said. 

House Speaker Nancy Pelosi, D-Calif., set a President's Day deadline for completing the plan. 

But multiple congressional sources indicated that talks to finalize the bill could keep the House and Senate in session through the weekend to complete the legislation. 

House Democratic leaders plan to discuss the issues with its members in a closed-door caucus meeting Tuesday afternoon at the Capitol. 

Senators reached a deal on its version of the legislation late Friday night. They debated the bill over the weekend and cleared a final procedural hurdle Monday evening in preparation for Tuesday's final vote. 

Rep. Louise Slaughter, D-N.Y., seemed particularly frustrated with the slow pace of the legislation in the Senate. 

"Tell me why the Senate is taking so long?" asked Slaughter. "I think the Red Queen in Alice in Wonderland wrote those rules over there."