With just two days left for Tuesday's US presidential election, a new poll has placed President Donald Trump in a seven-point lead against his Democratic rival Joe Biden in the battleground state of Iowa.

The state swung in favor for the Obama-Biden presidential ticket in 2008 and 2012, before flipping to Trump in 2016. Trump won 51.15 per cent of the votes in the 2016 presidential election, while his then Democratic rival garnered 41.74 per cent of the ballots.

According to the Des Moines Register/Mediacom Iowa poll released on Saturday, Trump was supported by 48 per cent of the registered voters in the state, while Biden garnered 41 per cent backing, The Hill news website reported.

Earlier in October, a Monmouth University Poll revealed that Trump was ahead with 48 per cent compared to Biden's 47 per cent. Both Trump and Biden campaigned in Iowa in October.The President rump is expected to hold another rally in the state on Sunday.

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Poll Delays

Meanwhile, Trump has claimed that voters will have to wait for weeks after the November 3 election day to know who wins the hotly contested race to the White House.

Campaigning in the battleground state of Pennsylvania, the President told supporters at a rally in Newtown on Saturday that they "are going to be waiting for weeks" for the election result to come, claiming that "very bad things" could happen while states are counting ballots after Tuesday's election, reports Xinhua news agency.

Pennsylvania election

Trump's comment came as the Supreme Court ruled on Friday that Pennsylvania election officials can accept absentee ballots arriving three days after election day, handing Democrats a victory in a legal fight. In the 2016 presidential election, Trump won in the state by garnering 48.18 per cent of the ballots.

"This is a horrible thing that the US Supreme Court has done to our country," said Trump, who has long insisted on the eveidence-less theory that universal mail-in ballots lead to voter fraud. Newtown was the first of the four campaign stops during his day in Pennsylvania -- where poll suggests his Democratic rival, Joe Biden, has enjoyed a consistent lead.

Biden was leading Trump by 51 per cent to 46 per cent, a Hill/Harris battleground poll revealed last week.With just two days left for Tuesday's showdown for the White House, Biden was in the lead against Trump by eight points also nationally, according to a Fox News poll released on Friday.

The poll revealed that 52 per cent of likely voters backed the former Vice President, while Trump had the backing of 44 per cent, The Hill news website reported. Also a poll released by The New York Times and Siena College released last week has placed the former Vice President eight points ahead of the President.