Hampshire, a day before the state's presidential primary election.

"As you go to vote tomorrow, this really is an option. Do you want more of the same, or do you want to go forward? Seventy percent, seventy percent of Americans have said they don't want a Trump-Biden rematch."

The 52-year-old former U.N. ambassador had at least five planned events on Monday.

Analysts have said the key to her success is voter turnout, with the politically moderate state's large number of independent voters allowed to take part in Tuesday's ballot.

New Hampshire may be Haley's last chance to prove she could be a viable alternative to Trump.

In the first nominating contest last week in Iowa, the former president coasted to a record-setting victory.

And polls show Trump leads Haley in New Hampshire by double digits.

'...we're leading by a lot...'

By contrast, the 77-year-old held just one event on Monday.

Trump continued urging his supporters to turn up for the ballot, in the hope of killing off Haley's chances of an upset.

He's been trying to portray Haley's gains in state polls as improper because they reflect growing support among independents.

He has also falsely claimed registered Democrats would be allowed to vote in the Republican primary.

"You got a lot of Democrats voting for her. You have a crazy election. 'Let's all get out and let's vote for somebody that we want to run against'. They want to run against her because she's so easy to beat."

In a dark turn of events, robocalls have been doing the rounds in the state - with fake audio of President Joe Biden telling Democrats to stay home on Tuesday (January 23).

White House Press Secretary Karine Jean-Pierre:

"That call was indeed a fake and not recorded by the president. I can confirm that. And so, I just want to be really careful, since it is a primary election... The president has been clear that there are risks associated with deep fakes. Fake images and misinformation can be exacerbated by emerging technologies."

Trump's campaign said it was "absolutely not" involved in the robocall.

The state's attorney general announced an investigation, saying the calls were an "unlawful attempt to disrupt the New Hampshire Presidential Primary Election and to suppress New Hampshire voters."