Donald Trump is running out of days to change the current trajectory of the presidential election, after a week where he pulled out of a debate scheduled for 15 October, and when Vice President Mike Pence apparently failed to win over more voters during his turn in the spotlight last week. Polls have grown so one-sided that Republicans fear a Democratic "blue wave" in November with control of the Senate also at stake. 

The current polling average is a 10.6-point advantage in favor of former vice president Joe Biden and running mate Senator Kamala Harris.

On 29 September, that average was just 6.1 points. Only one more major scheduled event remains on the calendar prior to the election day, the last debate on October 22.

Presently, Biden's favorable/unfavorable number is positive (more favorable) by 6.9 points, according to the averages compiled by RealClearPolitics.

Compare that with Clinton in 2016, when the former first lady was viewed more unfavorably on the eve of the election by 12.9 points. That's a swing of 19.5 points in favor of the Democrats. The president's average is 42.9 per cent favorable to 54.2 per cent unfavorable (minus -11.3).

If the current polling proves prophetic, the GOP's control of the Senate is nearly certain to be lost. Most Senate elections go the way of the state's presidential vote.

Texans on Tuesday joined a wave of Americans casting ballots at a record-setting pace, jamming early-voting polling places ahead of a Nov. 3 election showdown.

In Georgia, where early voting began on Monday, people waited five hours or more to cast ballots in record-breaking early turnout for a state that also features two competitive US Senate races.

With less than three weeks left until the election, Americans have cast more than 10 million early votes in person and by mail across the country, according to data compiled by the US Elections Project.

Meanwhile, Republican Senator Mitt Romney said Tuesday that the world is watching the "vile" US political scene with "horror" and attacked Trump's behavior.

"It is time to lower the heat," said Romney, one of the few prominent Republicans to have frequently criticized Trump since his 2016 election win.

Former president Barack Obama would "soon" join Joe Biden's campaign trail, a report said. Speaking to reporters on Tuesday before travelling to Florida, Biden said that his former boss will "be out on the trail".