Voters have tended to “punish” the party of the president in the past and vote against them.
Recent polling shows a low approval rating for the president. He began his second term as president with an approval rating of just over 50%, according to polling resource website Silver Bulletin, but in early October it was sitting at about 37%. Meanwhile 61% disapproved of him.
But not all seats in each chamber are competitive. Some are a safe bet for Republicans or Democrats.
The Cook Political Report, which analyses campaigns and elections, suggests that a limited number of districts are “toss-ups” that could be won by either party. Its latest update identifies 18 House districts, including in Florida and Michigan, and six Senate races, including in Alaska and Texas.
The vote is more unpredictable this year because of a battle between the two parties over the way voting districts in the House of Representatives are drawn.
Republicans tried to gain an advantage by creating more favourable electoral maps in certain states and Democrats followed suit.