U.S. voters go to the polls later Tuesday in midterm elections that could shift the balance of power in Congress and impact President Bush's policy agenda. Voters will choose all 435 members of the House of Representatives and 34 of the 100 Senators.
Historically, the party that controls the White House loses seats in midterm elections, so-called because they fall midway through the President's four-year term. But Republicans hope to defy that trend this year by increasing their control of the House and regaining the Senate, which the Democrats have controlled by a narrow margin.
The latest public opinion polls suggest the House will stay in Republican control.
The situation in the Senate is less clear. Control of that chamber could be determined by at least six races that remain too close to call.
Republicans are seeking to attract voters who are concerned about the nation's security in the aftermath of last year's September 11 terrorist attacks and possible war against Iraq. Democrats hope to mobilize voters who are worried about the sagging U.S. economy.
It is a point highlighted by political analyst Charles Cook.
"You have the economy pulling this election towards Democrats, and you have foreign policy concerns, terrorism, potential war with Iraq pulling in the opposite direction [toward Republicans]," he said.
There is much at stake for both parties and President Bush.
Republican control of the House and Senate would make it easier for President Bush to move his policy agenda forward as he prepares for a likely reelection campaign in two years.
But if Democrats retain their hold on the Senate, they could continue challenging Mr. Bush's agenda and force compromises on key issues.
Besides seats in Congress, voters will also choose 36 of the nation's governors.