What -- if anything -- will get done in Washington next year? That depends largely on which party is in charge of Congress. Here is a look at the possibilities:

1. Republicans win the House, Democrats keep the Senate: The outcome most likely to result in gridlock. Rep. John Boehner, R-Ohio, as House speaker, would preside over an expanded bloc of conservative Republicans and an agenda that could include further tax cuts, an attempt to repeal or modify the health-care overhaul law, a rollback of Wall Street regulations, and the return of unspent stimulus funds -- all of which Democrats, and the president, would fight. The GOP would regain control of committees, and Rep. Darrell Issa, R-Calif., likely to become chairman of the powerful House oversight committee, would launch wide-ranging hearings into White House policies and use his subpoena power to call administration officials to testify (just as Democrats did with Bush officials). House GOP leaders could seek ambitious entitlement and tax overhauls but would be rebuffed by the Democratic Senate, where Majority Leader Harry Reid, D-Nev., or his successor would emerge as President Obama's most important ally.

2. Republicans win the Senate, Democrats keep the House: This scenario is intriguing, if unlikely, considering there are 75 seats or more in the House -- the vast majority held by Democrats -- at risk of changing hands. But if this scenario happens, it would pit the new Senate majority leader, Mitch McConnell, R-Ky., against House Speaker Nancy Pelosi, D-Calif. -- two perennially underestimated masters of the inside game. McConnell would face the mighty task of herding a divergent GOP caucus that could include unpredictable newcomers such as Rand Paul, the Tea Party favorite.

Sixty would still be the magic number of votes needed to head off a filibuster, and McConnell would be forced to scrounge and bargain his way through the depleted, demoralized (and downright hostile) Democratic ranks to patch together support for the energy industry incentives and trade deals on his to-do list.

In the House, Pelosi would face pressure from moderate Democrats to ditch liberal priorities such as climate change that nearly sunk the party at the ballot box, and to cut deals with the Senate. Pelosi has said she wants to push ahead with an overhaul of the nation's immigration laws, but agreement between the parties on that volatile issue would probably be dead until after 2012.

3. Republicans win the House and Senate: If the GOP runs the table in November, it could take months of internal battling to sort out which version of the party will emerge as dominant: the old-school Republican establishment or the more ideological and rigid new guard. Possible priorities for an all-Republican Congress could include the termination of stimulus funding and the repeal of part or all of the new health-care law along with major changes to Social Security, including raising the retirement age.

A Republican-led Congress would turn Obama's veto pen -- or the threat of it -- into a powerful weapon. Moderate Democrats such as Sens. Claire McCaskill of Missouri, Mark Pryor of Arkansas, Mark Warner of Virginia and James Webb of Virginia could gain extraordinary leverage as dealmakers courted by leaders of both parties.

4. Democrats retain control of the House and Senate: The shock of nearly losing power after just four years would be certain to temper the Democrats' legislative ambition. The most chastened Democrats would be liberals who fought for the health-care and climate-change bills that distracted Congress from the jobs agenda voters say they would have preferred.

In the Senate, "control" could be especially difficult to exercise. It was already tough for Reid to win over enough Republicans on contentious votes to head off GOP filibuster threats. With even fewer Democrats, it would become even harder -- although the new GOP class may include a crop of moderates such as Mark Kirk of Illinois and Michael Castle of Delaware, along with independent Charlie Crist of Florida, who could prove amenable to bipartisanship.

In the House, the voting balance might change very little even with a larger number of Republicans. Assuming Democratic losses were mainly in conservative districts, Pelosi would lose members who were already tough to keep in line on difficult votes.