The Donald Trump campaign has admitted the Republican lags behind Hillary Clinton with just over two weeks to go before Americans cast their votes, BBC reported on Sunday.
"We are behind. She has some advantages,"
said his campaign manager Kellyanne Conway."We're not giving up. We know we can win this,"
On Friday, Trump made a rare admission that he could lose.
New polls suggest Clinton remains well ahead nationally and in several battleground states. Her campaign has predicted this is going to be "the biggest election in American history".
Campaign manager Robbie Mook told Fox News Sunday: "More people are going to turn out than ever before."
Polling in Republican strongholds like Utah and Arizona suggest these states could back a Democrat for the first time in decades.
That apparent change to the electoral map has prompted a shift in strategy for the Clinton camp, which is spending money on helping Democrats running in close House or Senate races.
Clinton said she didn't even bother responding to Trump anymore and would instead spend time "emphasising the importance of electing Democrats down the ballot".
Trump's campaign manager said the Clinton team had a huge financial advantage in how much they could spend on negative ads against Trump, and high-profile campaigners."She has a former president, who happens to be her husband, campaigning for her. The current president and first lady, vice president, all much more popular than she can hope to be,"
said Kellyanne Conway.
But this election does not feel over when you realise the depth of support Trump has on the campaign trail, she said.
However, Trump reflected on defeat for the first time on Friday when he said that - win, lose or draw - he would be happy with himself.
A day later, he announced a raft of measures for his first 100 days in office, that include used curbs on lobbying and new trade and climate change negotiations.
With just 16 days until the election, much of the recent focus has been on controversies linked to his campaign.
On Saturday, he promised to sue every woman who had accused him of sexual misconduct.
He also repeated his claims that the election is rigged, because of voter fraud at polling booths and media bias.