WASHINGTON (AP) Signature matches. Late-arriving absentee votes. Drop boxes. Secrecy envelopes.

Democratic and Republican lawyers already have gone to court over these issues in the run-up to Tuesdays election. But the legal fights could take on new urgency, not to mention added vitriol, if a narrow margin in a battleground state is the difference between another four years for President Donald Trump or a Joe Biden administration .

Both sides say theyre ready, with thousands of lawyers on standby to march into court to make sure ballots get counted, or excluded.

Since the 2000 presidential election, which was ultimately decided by the Supreme Court, both parties have enlisted legal teams to prepare for the unlikely event that voting wouldnt settle the contest. But this year, there is a near presumption that legal fights will ensue and that only a definitive outcome is likely to forestall them.

The candidates and parties have enlisted prominent lawyers with ties to Democratic and Republican administrations. A Pennsylvania case at the Supreme Court pits Donald Verrilli, who was President Barack Obama s top Supreme Court lawyer, against John Gore, a onetime high-ranking Trump Justice Department official.

Its impossible to know where, or even if, a problem affecting the ultimate result will arise. But existing lawsuits in Pennsylvania, North Carolina, Minnesota and Nevada offer some hint of the states most likely to be ground zero in a post-election battle and the kinds of issues that could tie the outcome in knots.

Roughly 300 lawsuits already have been filed over the election in dozens of states across the country, many involving changes to normal procedures because of the coronavirus pandemic, which has killed more than 230,000 people in the U.S. and sickened more than 9 million.