The presidential candidates each had 49.4 per cent of counted ballots, though Biden was ahead by 1579 votes as of Friday morning with 4169 left to count, Georgia's voting system implementation manager Gabriel Sterling said.

"With a margin that small, there will be a recount," Brad Raffensperger, Georgia's secretary of state, told reporters on Friday.

Officials said about 9000 military and overseas ballots were still outstanding and could be accepted if they arrive on Friday and are postmarked on Tuesday or earlier.

There are two ways of seeking a recount in Georgia.

A presidential candidate who loses by 0.5 per cent of the vote or less can force a recount by sending a written request to the secretary of state or a candidate can ask the secretary of state to conduct one by alleging a "discrepancy or error" in the vote tabulation.

In that case, state law gives the secretary discretion about whether to conduct a recount.

Local election officials in Georgia also can conduct recounts in their counties if they think there is a discrepancy in the results.

The southern state switched to new touch-screen voting machines this year.

After a voter makes their choices, the machine produces a marked paper ballot that's fed into a scanner that counts the vote.

Absentee voters - hundreds of thousands this year - filled out the same ballots, which also were fed into the scanners.

If the scanner cannot read the ballot, a bipartisan group of election officials reviews it to determine whether or how it should be counted.

A recount essentially repeats that process and in the past has not made big changes in the results.

Australian Associated Press