Why are some US Senate seats up for grabs? What you need to know in 500 words | 2024 US Election News

Thirty-four of the Senate’s 100 seats are up for grabs in November, the result of ongoing elections.

One race dominated this year’s election cycle in the United States: the battle between Kamala Harris and Donald Trump to win the White House.

But on November 5, Americans will also vote to fill other important vacancies outside the office of president. Many of those races will determine who controls Congress, a key power base.

One-third of the US Senate will be up for grabs, along with the entire House of Representatives. That means 34 seats in the upper house of Congress and 435 in the lower house.

But why are representatives voted on every two years – and senators every six? And why aren’t all 100 Senate seats up for grabs, like in the House?

Agitated races in the Senate

The answer goes back to the founding of the country, when the men who wrote the US Constitution decided to base the election of the Senate on a “three-tier system”.

According to the Senate report, “at the beginning of the first session of Congress in 1789, the senators were divided into three classes by lot with the members of one district assigned to different parties”.

The first group saw its term end in two years, the second in four and the third in six years.

“The elections that followed in all categories were for the Senate for six years,” the paper explained.

The idea was to provide stability to US politics. As a result of the Senate’s staggered voting system, two-thirds of senators remain in office every time there is a general election, once every two years.

How does this compare to the House of Representatives?

Things are different in the lower house of Congress, where all of its 435 members serve two-year terms and are eligible for election on every vote.

Running for re-election every two years puts House members at risk of losing their seats.

Still, some representatives have been in the House for decades: Former House Speaker Nancy Pelosi, for example, has served for 37 years.

What will happen on November 5?

The Democratic Party currently has a narrow hold on the Senate. The party and independents have 51 seats, compared to 49 seats held by the Republicans.

In order to control the chamber, Republicans need a large gain of one Senate seat if Trump defeats Harris in the presidential race.

This is because the vice president acts as the divisive vote in the Senate. If Republicans win the White House, Trump’s running mate JD Vance will fill that role and vote with Republicans.

If Harris wins — giving his vice president, Tim Walz, that power to cut ties — then Republicans would need a huge advantage of two Senate seats to take control.

Of the thirty-four Senate seats to be contested next month, twenty-three are Democrats or independents.

According to the latest polls, it may come down to several Senate races that appear to be neck and neck, including the state of Michigan.

Meanwhile, Republicans are looking to protect their control of the House of Representatives. Currently, there are 220 Republicans in the House, compared to 212 Democrats — with more than a dozen races considered toss-ups.