As counting is under way in America following closely fought elections that will determine whether Republicans win control of Congress, Jackie Fox takes a look at the key races and what makes them so important.

These elections are for Congress. Its main function is to make nationwide laws.

Congress is made up of two parts: the House of Representatives and the Senate.

Representatives serve for two years. There are 435 seats in the House and all are up for election. The number of Representatives per state is based on each state's population.

Whereas each state has two senators who sit for six years, just over one-third of the Senate is up for election.

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Whoever is in the White House usually suffers losses during the midterm elections. The problem for Joe Biden is that his party holds slim majorities in both chambers.

The Democrats currently have control over the House. While in the Senate, it's 50-50 but Vice President Kamala Harris has the tiebreaker vote there. Polls say Republicans will take the House.

It is a toss-up for the Senate.

Races to watch

The House

Abigail Spanberger, Democratic candidate for Virginia's Seventh District

Virginia's 7th Congressional District: Democratic Representative Abigail Spanberger, a former CIA officer has defended her seat and held off a Republican challenger.

Republicans believed they could do well here.

Virginia’s 10th Congressional District: This is another district which could be part of a pattern of wins for Republicans. It is a tough fight between Democratic incumbent Representative Jennifer Wexton and Hung Cao, a Navy veteran. Mr Biden won the area by 18.1 percentage points in 2020. However, during a governor race last year, that gap was closed.

New Jersey’s 7th Congressional District: It is a rematch between Representative Tom Malinowski (D) and Tom Kean Jr (R).

Rep Malinowski won the race by just over a point but due to recent redistricting in the area, Republicans have an edge under new congressional lines.

A win for Rep Malinowski will be very good news for Democrats.

Virgina’s 2nd Congressional District: Mr Biden won this area by 1.9 percentage points in 2020, but Democratic US Representative Elaine Luria has lost to Republican challenger Jennifer Kiggans.

The Senate

Races to watch are Nevada, Arizona, Georgia and Pennsylvania

There are several states which could determine which party takes over the Senate.

Races to watch are Nevada, Arizona, Georgia and Pennsylvania.

If two of those states go red - the Senate could turn Republican.

Democrats have already won the seat in the key state of Pennsylvania, with Democrat John Fetterman, who suffered a stroke in May, beating Republican opponent Mehmet Oz.

Election deniers

There are other races too for governor and local officials.

More than half of Republican candidates have raised doubts about the 2020 presidential election, such as Doug Mastriano, who is running for governor in Pennsylvania and Kari Lake in Arizona

If some of them win, they could be organising elections in 2024.

That is why Mr Biden has repeatedly said that democracy is on the ballot.