Both US presidential campaigns made impassioned pleas to supporters on Wednesday as they prepared for a series of legal battles over vote counting.
An email from the Trump campaign purporting to be from Vice President Mike Pence asked for donations and accused Democrats of manipulating the results of Tuesday’s poll.
“They’ve made it clear they’d rather destroy our nation than have four more years of our President’s incredible leadership,” the email read.
Joe Biden tweeted about midday with a link to the "Biden Fight Fund".
“To make sure every vote is counted, we’re setting up the largest election protection effort ever assembled,” he wrote.
“Because Donald Trump doesn’t get to decide the outcome of this election, the American people do.”
Republicans launched lawsuits in Michigan and Pennsylvania in the afternoon, telling supporters that Pennsylvania’s Secretary of State, Kathy Boockvar, had “tried her hardest to bake in a back door to victory” for Joe Biden.
Mr Trump also declared he was ready to go to the Supreme Court in the dispute.
His threat raised the spectre of the election being ultimately decided, as in 2000, by a high court ruling on how states can tally votes or conduct recounts.
The legal problems are mainly tied to the Covid-19 pandemic. Social distancing put a premium on being able to vote by mail.
Each state sets its own voting rules and many adopted or expanded mail-in vote programmes.
That required changing rules on how and when mailed ballots would be collected, verified and tabulated.
To accommodate millions of mailed ballots, state legislatures and election authorities extended the time for receiving ballots because of an overburdened US Postal Service, added time to count the votes, and took other steps to ease the process.
"It's clear that both candidates believe they still have a chance to win, so the fight is very much going forward. And the fight may take place in courts," said Ohio State University election law expert Ed Foley.
