The Democrats hold a narrow lead over the Republicans in the US Senate race in Mississippi, with both sides in a dispute over the counting of the remaining votes which could decide the outcome.
Lawyers for each campaign are preparing for a possible legal battle over the final results and weighing in on the examination of ballots.
The result could mark the end of almost 40 years of Republican control over Mississippi's senate seats and will determine the size of the Democrats' majority in the upper house.
Mississippi is the only US state which does not have a set procedure in place to trigger a recount - and the pressure is on to declare a winner with the state's 13 November deadline for certification approaching.
With 97% of the votes counted as of Friday, Democratic candidate Scott Colom is about 2,500 votes ahead of the incumbent Republican Senator Cindy Hyde-Smith.
Mississippi's Secretary of State Michael Watson said on Wednesday that 3,600 "absentee-by-mail ballots" were still to be counted. The state can accept these votes so long as they were postmarked by election day and are received by 10 November.
Watson said there are also an "unknown" number of provisional ballots, also known as affidavit ballots, to be counted. These are typically cast when a voter lacked the required identification to cast their vote. The deadline for voters to resolve any ID issues with provisional ballots, usually by providing acceptable photo identification, is also 10 November.
Mississippi Republican Party Chair Michael Hurst said on Thursday that they estimated there could be "approximately 20,000 outstanding ballots left to be counted".
Hyde-Smith's campaign said the same day that "thousands of votes remain to be counted from dozens of Republican counties" and it is "confident" this will secure her re-election. She has held the seat since 2018.
Colom said the election saw "historic voter turnout" and he is "confident that when votes are counted, we will flip this seat". If he wins, he would be the first black US senator elected in the state since 1875.
Colom said his campaign has an "an army of lawyers" ready to act - while the state Republican party said it has sent more than 50 volunteers, attorneys and observers across the state.
Lawyers from both campaigns have sent letters to Mississippi election officials about the counting of outstanding provisional ballots.
The Hyde-Smith campaign lawyers have requested that all 82 counties in the state keep all provisional ballots separate from regular or absentee ballots.
Their letter also requested that election officials preserve various records - including information on how the votes were processed - associated with the provisional ballots as "potential evidence" in a possible legal dispute.
The Colom campaign lawyers responded saying the move has "no legal authority whatsoever".
"Mississippi law does give any candidate a right to examine ballot boxes and their contents within 12 days after the relevant canvass and examination," says Ronald Rychlak, a law professor at the University of Mississippi. "Mississippi's affidavit-ballot statute also requires eligibility review and records concerning whether affidavit ballots were counted."
"Neither law, however, establishes a blanket requirement to segregate all affidavit ballots after they have been accepted," he adds.
The Colom campaign has said the request from Hyde-Smith's team could allow "a particular ballot to be traced to a particular voter", in violation of ballot secrecy laws.
"That's where he does have a more reasonable argument," says Rychlak, "as ballots in the US are private by law and when there's no clear procedure in place there could be a possibility a voter's privacy might be breached."
Recounts rarely succeed - just three out of 37 completed state-wide recounts across the US since 2000 have reversed a result.
However, in many states automatic recounts are triggered if a vote is very close, and in others there is an official process for campaigns to request one in a tight race.
Two states, Illinois and Tennessee, allow recounts if a candidate mounts a formal legal challenge.
Mississippi doesn't have a set procedure in place which allows for a result to be automatically recounted even if it's tight or contested.
It is effectively left up to judges in the state to decide how specific disputes should be resolved.
"Mississippi's lack of a formal recount procedure does not leave either campaign without a possible avenue to challenge the result," says Rychlak, "Ballot-box examination is an available post-election mechanism, and that can lead to discoveries that may result in a recount."
There could also be a legal challenge raised at a federal level - with the US Senate potentially having authority to determine who is entitled to the seat.
This would fall under Article I of the US Constitution as there is a provision which gives each chamber of Congress the power to be the "judge of the elections, returns and qualifications of its own members".
Additional reporting by Krystal Campos.
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