How Senate race in Georgia could make or break Joe Biden's presidency
Democrat wins in both Senate runoff seats could be a make or break moment for Joe Biden, even before his presidential rein begins on January 20.
Victory for Raphael Warnock and Jon Ossoff over their respective Republican rivals Kelly Loeffler and David Perdue would swing control of the Senate in favour of the Democrats.
But what does this mean and how would it impact Joe Biden's presidency?
What is the Senate?
The Senate, along with the House of Representatives, is one of two chambers which form the US federal government. Together, they make what is known as the US Congress.
The US constitution grants Congress the sole authority to enact legislation and declare war, the right to confirm or reject many Presidential appointments, and substantial investigative powers.
The Senate is composed of 100 Senators, two for each state. They are chosen by voters in their respective states.
With possibly Democrat wins in Georgia, it will mean both the Democrats and the Republicans will have 50 Senators each.
Why is the Senate result so important?
The Democrats already control the House of Representatives. To get control of the Senate means they would control both chambers of congress.
If Republicans Perdue and Loeffler win, they would hold a majority of 52-48. Just a win for one of them would give them a majority of 51-49.
But if both Democrats win, it would make it 50-50 each.
Vice-president elect Kamala Harris would then have the tie-breaking vote and Senate minority leader Chuck Schumer, rather than Mitch McConnell, would control the Senate.
In the highly-partisan politics of the US which often breaks along party lines, controlling both chambers, along with the presidency, reduces obstructions in passing reform.
It would bring the Senate and House of Representatives under Democratic control for the first time since President Barack Obama took office in 2009.
While some news networks have called one Senate seat for Democrat Raphael Warnock, the race between Jon Ossoff and Republican incumbent David Perdue is deemed to close to call. However this hasn't stopped Ossoff from declaring victory.
Results are expected on Wednesday.
What will the Democrats do with control of the Senate?
If the Democrats win both Senate seats, it will shift America's outlook for 2021 and beyond.
This is crucial for passing Mr Biden's agenda, including on issues such as the economy, healthcare and the environment - something where the two parties disagree hugely.
A win for the Republicans would limit how much Mr Biden could achieve as president as they would have power to block their agenda.
Mr Biden will sit in the White House after January 20 and Speaker Nancy Pelosi will would to pass his agenda.
The Senate has the power to approve or reject Mr Biden's nominees for cabinet and judicial posts.
Mr McConell has been an important power-broker during Donald Trump's presidency. Just last week, he blocked and attempt by Mr Schumer to approve a House-passed bill to increase direct payments in the $900bn coronavirus relief package from $600 to $2,000.
How long do Senators sit?
Senators are elected on six-year terms by the people of each state. Terms are staggered so around one-third of the Senate is up for reelection every two years.
This gives Joe Biden a two-year window before the next set of Senate elections.