The Republican Party retained control of both the Senate and House of Representatives in the November 2 elections, expanding its current majorities and extending the party's control of Congress.

Republican candidates won 19 of the 34 Senate seats up for election (voters elect one-third of the 100-seat body for six-year terms every two years), increasing their current 51-seat majority by four seats to 55. Because the Senate majority party sets the legislative agenda and chairs every Senate committee, party control of the Senate is important regardless of who is president or which party controls the House.

The 19 Republican victories included eight of the nine most competitive races -- in Alaska, Florida, Kentucky, Louisiana, North Carolina, Oklahoma, South Carolina and South Dakota. Republican John Thune's victory in South Dakota over current Senate Minority Leader Tom Daschle marked the first loss by a Senate leader of either party since 1952.

Another significant Republican victory came in Louisiana, where David Vitter became the first Republican senator from that state since the 1880s. He won a majority of votes in the state's open Election Day primary, avoiding the runoff election expected by some analysts.

The Democratic Party won 15 Senate seats, lowering its current 48-seat membership by four seats to 44. The 15 victories included the competitive race in Colorado, where Ken Salazar joined Republican Mel Martinez of Florida as the first Hispanic Americans elected to the Senate since 1977. Democrat Barack Obama, who won with a wide margin in Illinois, will be the first African American in the Senate since 1999.

In the House of Representatives, where all 435 seats are up for election every two years, Republicans won 231 races, expanding their current 22-seat majority by four seats.

Democrats won 200 races, resulting in a net loss of five seats. Three House races remained undecided -- in Louisiana and New York. The two uncalled races in Louisiana, where no candidate received over 50 percent of the vote, will be decided in a December 4 runoff election.

Despite the expanded Republican majority in the 109th Congress, both chambers are expected to remain partisan and combative, according to Republican political consultant Paul Pelletier.

For example, the expanded Republican majority in the Senate does not reach the 60-vote majority needed for actions such as stopping a filibuster, an extended floor debate used to forestall a vote. The new Senate could still find itself "deadlocked," said analyst Jim Thurber of the Center for Congressional and Presidential Studies at American University.

Because Congress has exclusive power to pass legislation and approve appropriations, it plays a crucial role in whether or not an administration can accomplish its goals. President Bush will need to engage closely with the new Congress and provide strong direction to push his legislative agenda, said Thurber.