What are the US midterms? A simple guide

There are four weeks to go until the US midterm elections, when voters take part in a ballot that could have a major impact on the rest of Donald Trump's presidency.On 3 November, Americans will choose members of Congress, which is made up of two parts - the House of Representatives and the Senate.Elections take place every two years, and when they happen in the middle of the president's four-year term of office, they are called the midterms.A key task of Congress is to create and pass federal laws - laws that apply nationwide.The outcome of the midterms will decide which political party - Trump's Republicans or opposition Democrats - controls Congress and how easy it is for the president to carry out his plans.The results are also seen as a measure of how happy people in the US are with the president's performance so far.All 435 members of the House - the lower chamber of Congress - will be elected. They serve fixed terms of two years. The House is commonly where proposed laws are introduced and debated.Meanwhile, 35 of 100 seats in the Senate, the upper chamber, will also be up for grabs. Senators serve six-year terms. Among other jobs, they approve or block proposed laws that ha...