Washington ? Today’s election will determine which party controls the 435-member House and the 100-member Senate. Here’s a look at what’s at stake and how the results could reshape Capitol Hill.

Question: What is the importance of the outcome, in terms of how Congress works?

Answer: The majority party sets the agenda in each chamber. For instance, Democratic control of either the House or Senate would pave the way for hearings on the Bush administration’s handling of the war in Iraq and a vote to increase the national minimum wage. If Republicans hold on to their majorities, they are expected to focus on making permanent some of the tax cuts enacted in President Bush’s first term.

Q: What can Democrats accomplish if they win the House but not the Senate?

A: They would gain new leverage to promote their priorities but face limits on what they could accomplish. If the GOP retains a Senate majority, almost assuredly it will serve as a firewall blocking bills passed by a Democratic House.

Q: What if Democrats take control of both the House and the Senate?

A: Legislatively, the impact would be limited.

Even Democrats’ best-case scenario gives them only a razor-thin Senate majority. So Republicans could use filibusters – which require 60 votes to overcome – to bottle up bills.

Compromises could be reached that allowed other measures to clear Congress, but at that point the word “veto” could make a comeback in Washington, D.C., lexicon. Bush has vetoed only one bill since taking office, but he is far less likely to sign legislation sent to him by Democrats, especially on social issues.

Even if Democrats’ measures were derailed, however, Capitol Hill would become the center of the Democratic universe, giving the party the chance to define and refine its ideas heading into the 2008 presidential race.

Q: How would a Democratic takeover of the House, the Senate or both affect the war in Iraq?

A: Democrats could have more hearings to spotlight their criticism of the administration’s policy and call witnesses to investigate what has gone wrong. But as commander in chief, Bush has wide latitude to pursue the strategy he thinks best.

Q: What if Democrats win a majority in the House by the barest margin?

A: Look for the conservative Democrats to get plenty of dinner invitations. On legislative matters, Republicans will try to cajole one or more of those lawmakers to defect to their side.

Likewise, Democratic leaders will work just as hard to hold on to their House majority.

Q: What happens if the Senate is split 50-50?

A: Republicans will be in charge because Vice President Dick Cheney, as the Senate’s presiding officer, would cast the tiebreaking vote.