Days before the biggest night of the presidential primary season, a new poll published Saturday will ring alarm bells for Joe Biden, who is seen lagging behind his likely White House challenger Donald Trump.

The nationwide survey of registered voters by the New York Times and Siena College found that if the election were held today, 48 percent would choose Trump with 43 percent for Biden.

The poll comes just ahead of "Super Tuesday" -- when more than a dozen US states hold presidential nominating contests in an exercise expected to finally end the challenge of Trump's remaining Republican rival, Nikki Haley.

The survey found President Biden struggling, despite many positive economic indicators, to persuade ordinary Americans that his policies are working for them.

Only one in four said the country is moving in the right direction, and more than twice as many voters said Biden's policies had hurt rather than helped them.

Significantly, the poll found waning support for Biden among some normally reliable Democratic constituencies, including blue-collar workers and non-white voters.

And while Trump has unified his base to a remarkable extent -- 97 percent of those who voted for him in 2020 said they would do so again -- only 83 percent of Biden's 2020 voters vowed to stick with him and a full 10 percent now back Trump.

The Times/Siena poll also noted a dramatic decline in Biden's support among less educated working-class voters of color.

Four years ago, Biden won that demographic by 50 points but the poll suggested the margin over Trump had since plummeted to just six points.

Much can happen in the months before the November 5 election, and Trump is still battling four indictments and 91 felony counts, though his core supporters appear to shrug those off.

And while Super Tuesday should see the end of Haley's challenge, analysts say Trump's dominant primary showing hides stiff opposition to his candidacy among the moderate Republicans and independents he needs to defeat Biden.

Nor is it clear how many skeptical Biden voters might grit their teeth and support him again rather than see Trump return to office.

The poll of 980 registered voters had a sampling error of plus or minus 3.5 points.