From cabinet appointments to coronavirus legislation, Biden's ability to enact his agenda hinged on the outcome of Georgia's two Senate run-offs.
With all eyes on the violence in Washington DC on Wednesday, it would have been easy to miss another key moment in US politics.
Donald Trump's replacement, Joe Biden, and his left-leaning Democratic Party, now have control of both houses of the US Congress.
After retaining the House of Representatives in November's election, on Wednesday the party gained control of the upper house, the Senate.
That came after two run-off votes in Georgia, which saw both Democratic candidates, Jon Ossoff and Raphael Warnock, triumph.
Euronews asked US political experts what this victory may mean for Biden and his administration.
Why victory doesn't give Democrats a free hand in the Senate
Even with Democrats winning both seats in Georgia, their leverage on the legislative process will remain limited, experts told Euronews.
It will be a "razor-thin majority", said Jessica Taylor, Senate and Governors Editor at the Cook Political Report.
"It's a 50-50", she told Euronews, meaning that the Democrats won't be able to pass a lot of the progressive legislation they campaigned for.
To advance their policy agenda, Democrats will need to work closely with moderate Republicans such as Senators Susan Collins of Maine or Lisa Murkowski of Alaska.
Five things Democrats can still do if they win
While victory in Georgia doesn't mean unfettered control for Democrats, it would still be significant in many ways.
Here are five things Democrats could do if they win.
1. Passing COVID-19 stimulus cheque
Passing the coronavirus stimulus cheque promised by Biden's team will be "the first thing that happens" if the Democrats take control of the Senate, said Tony Madonna, an Associate Professor in the Political Science Department at the University of Georgia.
Madonna said Democrats would be able to get the numbers to break the filibuster on this specific piece of legislation.
“Immediately, starting in the new year, Congress will need to get to work on support for our COVID-19 plan, for support to struggling families, and investments in jobs and economic recovery. There will be no time to waste,” Biden said in a statement after Congress approved the latest relief package.
2. Confirming appointments
"One implication of the Democrats taking control of the Senate is that it will allow President-elect Biden a clear path to confirm his cabinet appointments and, more importantly, his judicial appointments," said Donald P. Green, a Professor of Political Science at Columbia University.
Taylor noted that most Biden's cabinet nominees were centrists, which should facilitate the confirmation process in a split Senate.
The importance of administrative appointments shouldn't be underestimated, Madonna told Euronews, considering that lots of powers have been delegated to agencies such as the Securities and Exchange Commission or the Federal Communications Commission.
3. Pushing climate change policies
"We need bold climate action now. I will fight side-by-side with the Biden-Harris climate team to pass a bold climate and clean-energy agenda," said Senate Democratic leader Chuck Schumer.
In this area, "smaller things will likely go through," Madonna told Euronews. "It is possible that we will see an energy bill".
The Democrats may also want to repeal some of the regulations imposed by the Trump administration on the Environmental Protection Agency, Madonna added.
4. Conduct investigative hearings
A democratic win will "clear the path to investigative hearings by both the House and Senate on a range of topics, including alleged Russian hacking of federal agencies," Green told Euronews.
Top national security agencies confirmed Tuesday that Russia was likely responsible for a massive hack of US government departments and corporations, rejecting President Donald Trump’s claim that China might be to blame.
5. Dreamers act and tax bill a possibility
Madonna and Taylor both said a so-called "Dreamers act" to protect undocumented immigrants who were brought to the US as children could likely find support on both sides of the aisle.
A tax bill rolling back tax cuts on higher earners could also be a possibility, both experts told Euronews.
However, Madonna said this would likely require a "reconciliation" procedure to avoid filibustering, something which is still "a ways away".