Three ways the US midterm elections could reshape Congress

The US midterm elections could deliver a sweeping Democratic victory, a narrower gain for the party or a surprisingly strong result for Republicans, according to three scenarios set out by BBC North America correspondent Anthony Zurcher. The balance of power in Congress is at stake, and the outcome will shape President Donald Trump’s ability to advance his agenda during the next two years.

Public opinion surveys have given Democrats an apparent advantage, Zurcher writes, but polls have previously underestimated support for Trump. He says the scenarios are not predictions, but possible ways the results could unfold as votes are counted.

A Democratic wave — or a narrower gain

In the strongest Democratic scenario, the party would win the House by more than the 218 seats needed for a majority and take the Senate, including victories in some traditionally Republican states such as Texas or Kansas. Zurcher says early signs of such a result could include Democrats holding targeted House seats in Florida and winning Republican-held districts in states including North Carolina, Michigan, New York, Virginia and Kentucky.

A more modest Democratic outcome could still give the party a House majority, but by a narrow margin, while it gains only one or two Senate seats. Zurcher says that could leave party leaders struggling to unite their own members and produce a divided Congress, raising the prospect of legislative gridlock. Florida remaining comfortably Republican and Republican incumbents holding safer House seats would be among the signs of that scenario.

Republicans hold on

The third scenario has Republicans retaining both chambers. That would require the polls to be wrong and close races to break largely in their favour, with strong Republican turnout and support from independent and Hispanic voters who appeared to have turned away from Trump’s policies, Zurcher writes.

The House outcome could then remain uncertain until California finishes counting mail-in ballots. Republicans could also benefit from new congressional district boundaries in states including Texas, Florida and North Carolina. Early signs, Zurcher says, would include Republican senators Ashley Moody in Florida and Jon Husted in Ohio winning comfortably, alongside Republican gains in House contests.

The scenarios come as voters head to the polls on 3 November. The first results are expected after 23:00 GMT, but close contests and differences in state counting rules mean it could take longer to establish control of Congress. Our guide explains when the midterm results are expected