The likely candidates in the 2024 presidential match-up issued two starkly different new year messages to voters, with Joe Biden striking a note of cheerful optimism as his almost certain challenger Donald Trump, and Trump lashing out in a social media post laden with lies and conspiracy theories.

The president and first lady Jill Biden, vacationing in St Croix in the US Virgin Islands, offered a New Year’s message touting US job gains and the performance of the US economy during his administration – a message that voters have so far refused to accept.

In an interview with American Idol host Ryan Seacrest about his hopes for 2024, Biden said “[the American people] understand that we’re in a better position than any country in the world to lead the world”.

“We’re coming back, and it’s about time,” Biden said.

Asked about his memories of the previous year, Biden – whom Republicans in Congress have derisively called “Beachfront Biden” – said “people are in a position to be able to making a living now, and they’ve created a lot of jobs for over 14 million”.

In comments to reporters, Biden said his new year’s resolution was “to come back next year”.

“That’s the biggest one right there,” he said.

Trump, however, issued a simple: “Happy New Year. It will be a historic one. MAKE AMERICA GREAT AGAIN!!!” on his Truth Social platform.

Trump and former first lady Melania Trump welcomed 2024 with a concert by 90s rap star Vanilla Ice, and a Teenage Mutant Ninja Turtle “rock-out”, featuring Leonardo, Donatello, Raphael and Michelangelo, at his Mar-a-Lago home and private club, according to the Palm Beach Post.

Trump, the outlet reported, could be seen in videos toward the back of the room away from the dance floor as people danced to Vanilla Ice, whose real name is Rob Van Winkle, as he played his hit Ice Ice Baby.

A day earlier, Trump issued a more typically acidic message, predicting rival Joe Biden won’t “make it to the gate” in November. He repeated his unproven claims that the 2020 election was rigged and transposed the “crooked” moniker he used on Hillary Clinton to Biden.

“As the New Year fast approaches, I would like to wish an early New Year’s salutation to crooked Joe Biden and his group of radical left misfits and thugs on their never-ending attempt to destroy our nation through lawfare, invasion and rigging elections,” Trump said in the post.

“They are now scrambling to sign up as many of those millions of people they are illegally allowing into sour [sic] country, in order that they will be ready to vote in the presidential election of 2024,” Trump added.

The twin new year’s greeting arrived as the 2024 election shifts into high gear. Polling averages compiled by FiveThirtyEight show that 39% of Americans approve of Biden’s performance, with 55% disapproving – a gap that has doubled in 12 months.

But that comes as Trump faces a series of criminal complaints that, if any are heard and concluded with convictions before the election, may damage his standing among voters. With the White House gambling that Trump is the Republican candidate it can beat, there are few opportunities for slip-ups.

A survey released on Monday showed that Trump leads Biden among Hispanic and young voters – a key demographic that helped him win the presidency four years ago.

The USA Today and Suffolk University survey, condensed by the Guardian, found that Biden had 34% support among Hispanic voters surveyed, down from 65% in 2020, compared to Trump’s 39%. Biden’s support among Black voters had also declined, from 87% to 63%.

Among younger votes under 35, Trump leads Biden 37% to 33%, a spread that four years ago was 24 points in Biden’s favor.