Jon Ossoff is the youngest Democrat elected to the Senate since Joe Biden in 1973

• The Democrat Jon Ossoff has won his Senate runoff election in Georgia against the Republican Sen. David Perdue, as Decision Desk HQ and Insider projected early Wednesday.
• This makes Ossoff, 33, the youngest Democratic senator-elect since Joe Biden in 1973.
• Biden, the 78-year-old president-elect, won his first Senate seat in Delaware at the age of 30.
• Ossoff is also the first millennial to be elected to the Senate. The youngest incumbent senator had been Sen. Josh Hawley, a 41-year-old Missouri Republican.

Jon Ossoff has become the youngest Democrat to be elected as a US senator since Joe Biden in 1973.

Ossoff, 33, unseated incumbent Republican Sen. David Perdue in one of two runoff elections in Georgia, according to a projection early Wednesday by Decision Desk HQ and Insider.

Ossoff is also the first millennial to be elected to the Senate. The youngest sitting US senator is the Missouri Republican Josh Hawley, who is 41.

Ossoff previously worked as a US House staffer and is the CEO of an investigative-documentary company.

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A series of Ossoff's old tweets unearthed by Slate, with subjects ranging from the video game franchise "Grand Theft Auto" to the rapper Lil Jon, attest to his credentials as a child of the internet age.

"N00b 4 lyfe," Ossoff tweeted in April 2014. The year before, he tweeted: "Shouldn't autocorrect know 'crunkest' is a word?"

The last time a Democratic candidate as young as Ossoff won a Senate seat was in 1973, when a 30-year-old Biden defeated Republican Sen. J. Caleb Boggs to represent Delaware. Biden, now 78, is set to be inaugurated as the US president on January 20.

The youngest person ever elected to the Senate was John Henry Eaton, who was 28 when he was elected to represent Tennessee in November 1818.

The minimum age to be elected as a US senator is 30, according the US Constitution, but officials apparently forgot to ask Eaton how old he was.

Runoff elections were called in Georgia after no candidate in either Senate race secured more than the required 50% of the vote in the November 3 general election.

The Rev. Raphael Warnock, the other Democrat running for a Senate seat in Georgia, defeated Republican Sen. Kelly Loeffler, according to an earlier projection by Decision Desk HQ and Insider.

Warnock is the first Black man in Georgia to be elected as a US senator, and his victory brought an end to the 24-year losing streak for Democratic Senate candidates in the state.

In a Tuesday-night speech - in which he all but declared victory - Warnock paid special thanks to his mother, Verlene.

"The other day, because this is America, the 82-year-old hands that used to pick somebody else's cotton went to the polls and picked her youngest son to be a United States senator," Warnock said.

Wins for Warnock and Ossoff mean the Democratic Party now controls both the House of Representatives and the Senate.