US: As Republicans and Democrats make a last-minute push to tip the balance in close races before next Tuesday's mid-term elections, President George Bush will be campaigning this weekend in Nebraska.
Mr Bush is hoping to help Adrian Smith fight off a challenge from Democrat Scott Kleeb in a district that has been solidly Republican for 48 years.
The president's visit to Nebraska is a measure of how nervous Republicans are about next week's elections, which polls suggest will see Democrats taking control of the House of Representatives and possibly winning a Senate majority too. All 435 House seats are up for election on Tuesday, along with 33 out of 100 Senate seats and 36 state governorships.
The Democrats need to gain 15 seats for a House majority but at least 40 Republican-held seats are vulnerable, compared to just one Democratic-held seat.
Democrats need to pick up six Senate seats for a majority.
Political analyst Charlie Cook says: "The bottom line is that at this stage, Republicans should consider themselves lucky if their net losses stay in the 20-25 range in the House, four or five seats in the Senate and between five and eight governorships . . . but the chances of this thing going bigger - far bigger - still exist, and there are quite a few veteran Republican strategists, people who have done tons of races in all kinds of states and districts for many years, who are bracing themselves for that distinct possibility."
Today's Republicans are burdened with an unpopular president and a popular perception that Congress is tired and corrupt. It is the war in Iraq, however, that has proved the biggest drag on Republicans during this campaign, as the US public has turned decisively against a military adventure they see as unnecessary, costly and hopeless.
Democrats always expected to gain seats in the northeast of the country, but they are now poised to win in small towns and rural areas that are home to many soldiers serving in Iraq. Democratic candidates include Iraq war veterans, a retired admiral, a former navy secretary and a former senior CIA officer, all of whom oppose the war.
Republicans in tight contests have sought to distance themselves from the president over Iraq, calling for the resignation of defence secretary Donald Rumsfeld or demanding a change of course.
A Democratic majority in the House would have an immediate and powerful impact on the last two years of Mr Bush's presidency, with investigations into everything from the preparation and conduct of the Iraq war to the administration's controversial energy policy.
Nancy Pelosi, who would probably be Democratic House speaker, promises to work with Republicans in Congress and the administration and to respect the rights of the minority.
Unlike the more gentlemanly Senate, however, the House is a place where the minority traditionally has few rights, with the majority party controlling every step of the process of proposing, debating and passing legislation.
Democrats will immediately introduce Bills to increase the minimum wage and to reform the system that subsidises prescription drugs for senior citizens. They will seek to implement all the recommendations of the 9/11 Commission for improving homeland security.
The Iraq Study Group, a bipartisan body chaired by former secretary of state James Baker and former congressman Lee Hamilton, will report within the next few weeks on US policy options in Iraq and is almost certain to recommend a new approach.
A Democratic majority in Congress would increase pressure on the administration to change course and to start redeploying US forces, perhaps in co-operation with Iraq's neighbours, including Iran and Syria.
There is scope for co-operation between Democrats and the Bush administration, notably on immigration reform and education, where the president's views are closer to those of Democrats than to many Republicans.
After 12 years of almost unbroken domination of Congress, defeat next week would leave Republicans surveying the wreckage of their dream of a fundamental realignment of US politics. The party's success in recent years has depended on holding together a coalition of economic liberals, national security hawks and social conservatives, while attracting growing numbers of African-American and Hispanic voters.
If next week's election goes as polls are predicting, it will end the careers of many of the dwindling group of moderate Republicans in northeastern states, senators like Ohio's Mike DeWine and Rhode Island's Lincoln Chafee, and congressmen like Connecticut's Christopher Shays.
Polls show black voters turning away from Republicans over the war, and Hispanic voters, the fastest-growing group in US politics, abandoning the party because of its tough line on immigration.
Former president Bill Clinton has used campaign speeches to paint the Democratic Party, not only as the party of the centre but as the representatives of conservatives as well as progressives.
"This is a sweeping, deep, big thing . . . If you're a conservative on the budget, on law enforcement, on the rule of law, when it comes to the environment, on the conservation of our military resources, you have to be a Democrat," he said in San Francisco this week.
With the US public angry about the war, disillusioned with the president and contemptuous of a Congress they see as lazy and corrupt, strategists from both parties believe Democrats may be on the verge of a political tidal wave that could reconfigure US politics for years to come.
The new intake of Democrats is likely to include many moderates who are conservative on social issues, defence and national security, while the loss of moderate Republicans could leave that party appearing out of step with mainstream America.
The loss of both chambers of Congress could leave Republicans divided and demoralised as they face into the 2008 presidential campaign, which will begin as soon as next week's elections are over. For the Bush administration, it would mean two years of investigations into all the perceived wrongdoings of the past six years as the president struggles with diminished authority to implement what remains of his political agenda.