Bill de Blasio is going up against Hillary Clinton as the Democratic presidential candidate, it has been claimed.

The Mayor of New York is allegedly entering the race as a 'leftist' alternative to Clinton in the hopes that this will see him represent the party in the 2016 elections.

This claims come in the wake of a television appearance last week, just hours before Clinton announced her candidacy, where de Blasio refused to back her.

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The Mayor of New York is allegedly entering preparing to run for president as a 'leftist' alternative to Hillary Clinton, according to a source within the Democratic Party

De Blasio's intentions to throw his hat in the ring as Democrat presidential candidate comes from a 'national party operative', according to the New York Post.

The mayor's bid for presidency is backed by the Working Families Party, and he hopes that left-leaning 'progressive activists' will join them in supporting him over the coming months, the source claims.

'De Blasio and his advisers are trying to position the mayor as the 'draft' candidate for the left in 2016. That's why he refused to endorse Hillary last week,' the party operative told the Post.

The 53-year-old has yet to back Clinton, despite the fact that he was campaign manager of her U.S. Senate bid in 2000, an indication that the rumours of his intentions to run for president may be true.

The New York City mayor, known to be more liberal than Clinton on most issues, surprised many Democrats when he declined to endorse his former boss during an interview last week.

Behind her back? Bill de Blasio has yet to endorse Hillary Clinton as the Democrats' presidential candidate, despite the fact that he was campaign manager of her U.S. Senate bid in 2000

The New York City mayor, seen inspecting a Bronx apartment as pary of an affordable housing project, said he will not endorse Clinton until he can 'see an actual vision of where they want to go'

Appearing on Meet The Press, De Blasio said he would withhold his blessing 'until I see an actual vision of where they want to go.'

'She's a tremendous public servant,' the mayor continued. 'I think she is one of the most qualified people to ever run for this office. And by the way, thoroughly vetted, we can say that. But we need to see the substance.'

De Blasio has taken several steps to raise his profile in recent weeks, including making a bid for the 2016 Democratic National Convention, hosting a meeting of liberals at Gracie Mansion this month and traveling to Nebraska and Iowa — site of the first nominating caucus — last week to champion the fight against income inequality.

Today, Clinton is scheduled to arrive in New Hampshire as she steps up her campaign for the Democratic nomination.