Jon Ossoff, who shot to national prominence during a 2017 special House election, is running for Senate in Georgia, challenging Republican Sen. David Perdue for his seat.
"We believe the battle that began in Georgia in 2017 will be won in Georgia in 2020 when we flip the Senate and win the White House," Ossoff says in a campaign video Tuesday announcing his bid for US Senate.
In 2017, a special election was called after Tom Price vacated his seat in Georgia's sixth district to serve in President Donald Trump's administration. Ossoff nearly won against Republican Karen Handel in what was, at the time, the most expensive House race in history and seen as a gauge of Trump's popularity.
A former congressional staffer and documentary filmmaker, Ossoff, never having held public office before, quickly emerged as an online fundraising superstar, raising $23 million for his campaign.
Ossoff nearly won the seat in the longtime conservative stronghold outright during the April jungle primary election, falling about two points short of avoiding a runoff election.
Democrats have aimed to make Georgia competitive in the presidential race and nearly won the governor's race last year.
Georgia Rep. John Lewis, a civil rights icon for whom Ossoff worked as a congressional aide, endorsed Ossoff for US Senate, saying in a statement that he's "ready to work tirelessly to elect him."
"Jon's 2017 campaign sparked a flame that is burning brighter than ever, in Georgia and across the country," Lewis said.
Georgia will have another Senate seat on the ballot in 2020 after Georgia Sen. Johnny Isakson announced that he will resign at the end of the year due to health concerns. Republican Gov. Brian Kemp will appoint a replacement for Isakson until a special election held in November 2020 will determine who will serve the remainder of his term.
CNN's Eric Bradner contributed to this report.