US President Donald Trump has attacked Cindy McCain, the widow of Republican maverick John McCain, for her endorsement of his Democratic rival, Joe Biden.
With 41 days until the election, the race between Mr Trump and Mr Biden has narrowed in key states.
“I hardly know Cindy McCain other than having put her on a committee at her husband’s request,” Mr Trump tweeted on Wednesday, hours after Ms McCain announced her support for Mr Biden.
He dismissed her move, calling Mr Biden “John McCain’s lapdog” and saying that “Cindy can have Sleepy Joe".
Ms McCain announced her support for Mr Biden late on Tuesday evening, almost a month after appearing in a video at the Democratic National Convention.
“My husband John lived by a code: country first," she tweeted. "We are Republicans, yes, but Americans foremost.
"There's only one candidate in this race who stands up for our values as a nation and that is Joe Biden."
Her endorsement holds extra weight in the battleground state of Arizona, the result of which could help to tip the election on November 3.
Arizonans are waking up to some pretty big news on the front page of @azcentral. 🌵🚀 pic.twitter.com/E1VeVMgqvH
— Geoff Burgan (@GeoffBurgan) September 23, 2020
Polls released this week are showing a dead-heat race between Mr Trump and Mr Biden in Georgia, Iowa, Florida and Arizona.
Both candidates will be travelling or sending surrogates to these states and the Biden campaign is using its $141 million (Dh517.8m) financial advantage over Mr Trump’s to air TV ads there.
The two candidates will face off for the first time next Tuesday in a televised debate moderated by Fox News anchor Chris Wallace.
The first of the three debates between the two will address six topics: the candidates’ records; the Supreme Court; the pandemic; the economy; race and social unrest; and the integrity of the US election.
Mr Trump again on Tuesday questioned the process of mail-in-ballots, linking with to the Supreme Court nomination after the death of Justice Ruth Bader Ginsburg.
He said a Full Court would be needed to have him elected if he contested the result.
"We need nine justices," Mr Trump said. "You need that with the unsolicited millions of ballots that they're sending. You're going to need nine justices."
He plans to announce his new Supreme Court nominee at 5pm on Saturday.
Conservative judge and former law professor Amy Coney Barrett is believed to be a favourite, having been invited to the White House twice this week.
Senate Republicans are hoping for a swift vote before the election on November 3.
Hearings for the nomination could begin on October 12, with a final vote by the full Senate on the week of October 26, Bloomberg reported on Wednesday.
But Democrats, a minority in the Senate, could use a delaying tactic to slow the nomination process.
Brad Jones, a research associate at the Pew Research Centre, told The National that the US public was increasingly divided along party lines and it was unclear how the Supreme Court fight would affect the election.
“Not much has moved people’s preferences,” Mr Jones said, despite Mr Trump’s unconventional way of running his campaign.
