Combo photo shows U.S. President Donald Trump (L) and 2020 Democratic nominee Joe Biden delivering their respective speeches on different occasions. (Xinhua)

Democratic US presidential nominee Joe Biden said on Saturday that "the only way" he could lose to US President Donald Trump was through "chicanery," before clarifying that he will accept the election result.

Biden encouraged potential voters at a campaign stop in the must-win battleground of Pennsylvania, telling them to "make sure to vote because the only way we lose this is by the chicanery going on relative to polling places."

Biden referenced what he said were attempts by Trump to discourage voting, including casting doubt on the security of mail-in ballots and the encouragement of potentially intimidating Republican poll observers.

When asked directly, Trump has repeatedly avoided confirming that he would accept the result of the election.

Before leaving the state, Biden told reporters his comments were "taken a little out of context" and added that "I'm going to accept the outcome of this election, period."

Biden has previously said that his single greatest concern was Trump trying to "steal" the victory. His campaign has recruited hundreds of lawyers and volunteers to prevent Election Day chaos.

Trump's campaign has accused Biden of lying and stoking fear.

Election experts have been on edge about the process, given chaos and legal challenges during primary elections held amid the outbreak of the novel coronavirus.

US Republican Senator Ted Cruz warned Friday that his party could face a "bloodbath of Watergate proportions" in November's election if voters are pessimistic about Trump's handling of the economy and the pandemic.

"I am worried.... It's highly volatile," Cruz, a staunch Trump ally, told CNBC television, although he noted that Trump could win reelection if voters feel the country is recovering from the pandemic-driven economic crisis.

But he also spoke of the possibility of landslide losses similar to those in 1974, when Democrats expanded their majorities in the House and Senate in the first election following the Watergate scandal and the resignation of Richard Nixon.

Democrat Jimmy Carter won the White House in 1976 in the first post-Watergate presidential election.

"If on election day people are angry and they've given up hope and they're depressed... I think it could be a terrible election," Cruz added.

"I think we could lose the White House and both houses of Congress, that it could be a bloodbath of Watergate proportions."

Trump has trailed his Democratic rival Biden in nearly every major poll in 2020.

Democrats are widely expected to keep the House in the November 3 election.

Reuters - AFP