Joe Biden's party won a new seat in the US Senate with the victory of Democrat Raphael Warnock in Georgia.
The incumbent senator defeated Republican Herschel Walker, protégé of former US President Donald Trump.
The victory confirms the narrow Democratic majority in the upper house of Congress.
Biden, who should have suffered a tough defeat in the midterm elections, emerges strengthened from this electoral round.
The American president had shown extremely confident a few minutes before the announcement of the results.
"We will win, we will win in Georgia," he told reporters.
This victory does not change the balance of power in the US Congress: the Democrats had already made sure to maintain control of the Senate after the first round of legislative elections in November.
Republicans took control of the House, but with a much smaller than expected majority.
But this new seat gives more freedom to Biden's party, which has been governing with a very narrow majority for two years: 50 seats out of 100. It will allow him, among other things, to exercise greater influence in essential parliamentary committees.
And it will greatly limit the influence of a moderate Democratic senator, Joe Manchin, the grave-runner of several major Biden administration projects.
With this seat, Republicans hoped for their part to secure broader blocking powers to Biden's policies.