LIVE UPDATES: See the full results of Georgia's presidential and congressional primaries

• Georgia is holding its presidential primary and several competitive congressional primaries on Tuesday.
• In addition to the Democratic primary for US Senate, there are hotly contested primaries for three US House seats in Georgia's 7th, 9th, and 14th congressional districts.
• Polls in most of Georgia closed at 7 p.m. in most of the state, but widespread problems with Georgia's administration of in-person voting led to poll closing times to be extended to as late as 10 p.m. in some places.
• The significant increase in voters casting ballots by mail and resulting delays in ballot counting means that some races may not be called until later this week.

Polls in most of Georgia closed at 7 p.m. in most of the state, but widespread problems with Georgia's administration of in-person voting led to poll closing times to be extended to as late as 10 p.m. in some counties and precincts.

The massive increase in Georgia citizens voting by mail this year due to the COVID-19 pandemic means ballot counting will take longer than usual and many races will not be called until late Tuesday or Wednesday.

The biggest races:

Former Vice President Joe Biden officially secured 1,991 delegates, the majority threshold requires to officially clinch the Democratic nomination before today's elections. But he expanded his delegate lead with Tuesday's primaries both in Georgia and West Virginia.

Biden became the presumptive nominee when Sen. Bernie Sanders, his last major opponent, dropped out of the race and ceased campaigning on April 8. Sanders is still staying on the ballot in the remaining states left to vote to earn delegates that will give his camp representation on key Democratic National Convention committees.

Georgia accounts for 105 pledged delegates in the Democratic nomination, with 68 allocated between the state's 14 House districts and the remaining 37 allocated at the state level.

There are also a number of important congressional primaries taking place in Georgia, including the Democratic primary for US Senate to face GOP Sen. David Purdue this November.

The Democratic field includes Jon Ossoff, a documentary filmmaker and the 2017 Democratic nominee for the special election in Georgia's 6th district, former Columbus, Georgia Mayor Teresa Tomlinson, trucking executive Sarah Riggs Amico, and civil rights attorney Maya Dillard Smith.

Georgia is a runoff state, meaning that if no one candidate clears the field with over 50% of the vote in any of the primaries taking place today, the race will go to a runoff between the top two vote-getters on August 11.

The Democratic US Senate primary taking place today is separate from the special election for Georgia's other US Senate seat, currently held by Sen. Kelly Loeffler, who was appointed to the Senate this January. In the November 3 general election, Loeffler will run in a special jungle election with candidates from all parties, with the top two potentially advancing to a December runoff.

In the House of Representatives, there are crowded Democratic and Republican primaries in Georgia's 7th congressional district, a highly competitive open seat in the Atlanta exurbs being vacated by GOP Rep. Rob Woodall.

Trump carried Georgia's 7th district by 6.3 percentage points in the 2016 presidential election. But Georgia's 7th, which is very similar to many of the diverse, suburban districts Democrats won back in the 2018 midterms, is a top target for Democrats to flip this year after Woodall won re-election by just 419 votes over 2018 nominee Carolyn Bourdeaux.

Bourdeaux, a public policy professor, is now running again for Democratic nomination and will go to an August 11 runoff against Georgia House Representative Brenda Lopez Ramero. She currently leads the field in fundraising and has secured the endorsements of Rep. John Lewis and Democratic House Caucus Chair Hakeem Jeffries.

In Tuesday's primary, Bourdeaux and Lopez Ramero defeated State Senator and attorney Zahra Karinshak, businessman Rashid Malik, and progressive activist Nabila Islam, who has been endorsed by Reps. Alexandria Ocasio-Cortez, Ilhan Omar, and Ro Khanna.

Bourdeaux or Lopez Ramero will face physician and US Navy and Marine Corps veteran Rich McCormick, who won the Republican primary for the seat outright, defeating State Senator Renee Unterman, and businesswoman Lynne Homick.

The Cook Political Report, Sabato's Crystal Ball at the University of Virginia Center for Politics, and Inside Elections all rate the seat as a toss-up in the general.

There are also competitive GOP primaries in two open safe Republican-held seats in Georgia.

In Georgia's 9th congressional district, which current Rep. Doug Collins is vacating to run for Georgia's other US Senate seat against Loeffler, State Representative Matt Gurtler and gun store owner Andrew Clyde advanced through the crowded Republican primary to a runoff, beating state legislators Kevin Tanner and John Wilkinson, and attorney Ethan Underwood.

Trump carried the district, located in the northeast corner of the state, with over 77% of the vote in 2016.

There's also a competitive Republican primary in the 14th congressional district being vacated by Rep. Tom Graves, also a safe GOP seat situated in the rural northwest part of the state.

While Decision Desk HQ has not called the race, businesswoman Marjorie Greene and neurosurgeon John Cowan, appear likely to advance to a runoff. Georgia State Representatives Bill Hembree and Kevin Cooke and real estate executive Ben Bullock also ran in the primary.

Greene, who is largely self-funding her campaign, aired an eye-catching ad denouncing "antifa" as terrorists, accusing George Soros, "Hollywood Elites," and Biden staffers of financing antifa and, with a gun in hand, warned antifa to "stay out of Northwest Georgia."

A pandemic election meltdown in the Peach State

Voters throughout the entire state and especially in the metro Atlanta area faced immense difficulties voting in Georgia's primary election on Tuesday because of widespread problems with new electronic machines malfunctioning and shortages of paper ballots.

A combination of understaffed, consolidated polling places, problems with Georgia's brand-new voting machines, and undertrained poll workers not knowing how to operate the machines led to hours-long lines to vote in places including Fulton, Gwinnett, Cobb, and DeKalb counties.

While some voters in polling places with technology problems were able to cast provisional ballots, others were not, and many people had to leave voting lines before getting the chance to cast a ballot.

In addition to poll closing times being extended in many counties, the disastrous election administration in some places led the Secretary of State's office to announce investigations into Fulton and Gwinnett counties.

Georgia, which allows voters to request an absentee ballot without an excuse, broke an all-time record for the proportion of voters casting ballots by mail after Secretary of State Brad Raffensperger's office sent all 6.9 million active registered voters in the state an absentee ballot application.

As of Tuesday morning, 1.3 million Georgians requested absentee ballots and a little over one million voters had returned their ballots, vastly exceeding the 37,000 voters who voted absentee in Georgia's 2016 primary election and the 209,147 who did so in the 2016 general election.

As the Atlanta Journal-Constitution reported on Monday, both parties have enthusiastically embraced mail-in voting. On Tuesday, 50% of mail-in ballots came from those who requested Democratic primary ballots and 48% came from voters who requested Republican primary ballots, according to election analyst John Couvillon.

Despite the high participation among voters of both parties statewide, Georgia's efforts to scale up their absentee and mail-in voting weren't without challenges, some which led to voters not receiving the ballots they requested.

The election office in Fulton County, which includes the city of Atlanta and is the state's most populous county, is under investigation amid of reports of unknown numbers of absentee ballot requests completely disappearing from the county's internal systems, leading to many voters, including a state senator, not getting their ballots sent to them in time.

Georgia also held several days of early in-person voting to help reduce crowding at vote centers, but shortages of poll-workers and fewer open polling places than normal caused many voters to wait hours in line to vote early at some polling places in the metro Atlanta region.