US voters are going to the polls for midterm elections, with control of the Senate among the issues to be decided.
As public campaigning gives way to the privacy of the voting booth, the make-up of the lower chamber, the House of Representatives, and three dozen state governorships are also at stake.
President Barack Obama is not on the ballot midway through his second term, but acknowledges that his policies are.
Republicans have rushed to agree, given Mr Obama's low approval ratings. They said they would work to change the president's policies but offered little by way of specifics.
Democrats did not defend the president so much as insist they are independent of him.
The main prize after the 4 billion dollar (£2.5 billion) campaign is Senate control in a contest that sprawls across three dozen states.
With numerous competitive races and the possibility of run-offs, the outcome may not be known for days.
The polling is seen as all but certain to give opposition Republicans control of both chambers of Congress.
The question is whether Washington's legislative paralysis would deepen if the president's Democrats lose their majority in the Senate.
Polling across the board gives Republicans well over a 50% chance of turning out at least six incumbent Senate Democrats or capturing seats left vacant by Democrat retirements. Thirty-six Senate seats are on the ballot.
There was little suspense about the races for all 435 seats in the House of Representatives, beyond the size of the new Republican majority. A gain of 13 seats would give Republicans their largest representation since they had 246 in 1946. Democrats concentrated on protecting their incumbents.
Democrats weighed down by Mr Obama's low approval ratings kept their distance from him and looked to a costly get-out-the-vote operation in the most competitive Senate races to save their seats and their majority. They were working to reach out to minority, women and young voters who tend to sit out elections when the presidency is not at stake. Those voters tend to back Democrats.
About 10 Senate races have drawn most of the attention, but Democrats are at a disadvantage because these are either in Republican-leaning states carried by Mitt Romney in the 2012 presidential election or evenly divided swing states. In these competitive states, astronomical spending and numerous attack ads have dominated campaigning - with few ideas offered on how to govern the nation. Serious discussions about trade and energy policies, deficit spending, climate change, immigration and other knotty issues rarely emerged.
The president's party traditionally loses seats in a midterm election. Mr Obama and the Democrats face an electorate that remains deeply concerned about the direction of the economy, though it has shown signs of improvement. Terrorism has re-emerged as a top issue, as well as the threat posed by the Islamic State group in Iraq and Syria, and polls showed Republicans have an edge on handling both issues. And Mr Obama's administration has faced questions about its competence, from Secret Service scandals to the bungled roll-out of the president's health care programme, known as Obamacare.
Republicans were all but assured of winning Democratic-held seats in West Virginia, Montana and South Dakota, and Democrats held out little hope that senator Mark Pryor could win re-election in Arkansas.
Polls suggested that races for Democratic-held seats in Iowa, Colorado and Alaska have tilted for Republicans - although Democrats said their get-out-the-vote operation made any predictions unreliable.
Democratic incumbents also faced competitive races in New Hampshire and in North Carolina where Democrats said they had an edge - although Republicans disagreed.
Strategists in both parties said candidates in Louisiana and Georgia were unlikely to reach the 50% threshold needed to avoid a run-off. The wildest wild card of all was in Kansas, where polls said 78-year-old Republican senator Pat Roberts was in a close race with independent Greg Orman in a state that has sent Republicans to the Senate for nearly 80 years.
Democrats had hoped to pick up the Kentucky seat held by Senate Republican leader Mitch McConnell, but recent polls showed him building a lead over Democratic challenger Alison Lundergan Grimes. Mr McConnell would be in line to control the Senate's agenda as majority leader if Republicans win.
That left Georgia as the Democrats' best opportunity to pick up a Republican seat, with Democrat Michelle Nunn, whose father served four six-year terms in the Senate, facing Republican businessman David Perdue.