Donald Trump has turned a surprise opening-day appearance at his party's scaled-down national convention into an opportunity to question the integrity of the upcoming election.
The US President warned his fellow Republicans their opponents may "steal" November's election, as his party anointed him as their candidate.
The president, who was not scheduled to deliver his keynote convention address until later in the week, nevertheless made multiple public appearances throughout the first day of the convention.
"The only way they can take this election away from us is if this is a rigged election," President Trump told hundreds of Republican delegates gathered in North Carolina, raising anew his unsupported concerns about Americans' expected reliance on mail voting during the pandemic.
Experts say mail voting has proven remarkably secure.
The GOP convention marks a crucial moment for President Trump, a first-term Republican president tasked with reshaping his campaign.
As a formality, he was officially nominated to be the Republican nominee earlier on Monday at the convention in the city of Charlotte.
Mr Trump also warned of a "rigged" election in 2016, as he trailed Hillary Clinton in the polls.
The president is due to give a speech to the party convention on Thursday. It is unusual for a candidate to address the convention before their formal acceptance speech.
Supporters at the convention cheered Mr Trump as he made his remarks, and he interjected as they began to chant "four more years”.
“If you really want to drive them crazy, you say 12 more years," he said.
The 22nd Amendment to the US Constitution states presidents are only permitted to serve two terms, for a total of eight years in office.
