Elizabeth Warren calls for change as she makes 2020 presidential bid official

Democratic senator Elizabeth Warren has made her bid for the US presidency official, during a 44-minute speech in sub-zero temperatures.

Speaking in Lawrence, Massachusetts, Ms Warren grounded her 2020 campaign in a populist call to fight economic inequality and build “an America that works for everyone”.

Ms Warren delivered a sharp call for change, and decried a “middle-class squeeze” that has left “too little accountability for the rich, too little opportunity for everyone else”.

She and her backers hope that message can distinguish her in a crowded Democratic field and help her move past the controversy surrounding her past claims to Native American heritage.

She has been forced to apologise for claiming on several occasions in her early political career that she was of Native American descent.

Those claims led her to be criticised by the current president, Donald Trump, who has referred to her as "Pocahontas".

Despite their sparring history Ms Warren avoided taking direct jabs at President Trump - instead weaving specific policy prescriptions, such as the elimination of Washington "lobbying as we know it", into her remarks.

She aimed for a broader institutional shift, urging supporters to choose "a government that makes different choices, choices that reflect our values".

Ms Warren announced her campaign in her home state of Massachusetts at a mill site where largely immigrant factory workers went on strike about 100 years ago, a fitting forum for the longtime consumer advocate to advance her platform.

She was scheduled to travel later in the day to New Hampshire, home of the nation’s first primary, where Ms Warren could have an advantage as a neighbouring-state resident with high name recognition.

Ms Warren intends to spend Sunday in Iowa, where the lead-off caucuses will be the first test of candidates’ viability.

She was the first high-profile Democrat to signal interest in running for the White House, forming an exploratory committee on New Year’s Eve.