A group of nearly 40 staffers who worked for Elizabeth Warren’s presidential campaign has endorsed Bernie Sanders in an open letter, calling on their supporters to "persist together" in the battle for the White House.

In a letter published to Medium.com on Tuesday titled “Team Warren for Bernie Sanders”, the group of organisers and campaign directors stated their goals included working “to consolidate those who are ready to jump from Warren to Sanders immediately and build a community to facilitate the transition”.

The campaign staffers also said they wanted to reach out to Ms Warren’s supporters and urged them to support the Vermont senator in his bid against former Vice President Joe Biden for the Democratic nomination.

Those new forms of outreach, the letter stated, would use the foundation built by Ms Warren’s campaign and “the grassroots networks that we have cultivated” throughout the Democratic primaries.

The letter comes just five days after Ms Warren, once considered a potential frontrunner in the Democratic primaries, dropped out of the race. It was published as voters in six battleground states participated in primaries across the country following last week’s Super Tuesday — with Mr Sanders fighting to maintain his campaign against Mr Biden’s newfound frontrunner status.

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“Elizabeth ran a campaign on intersectional policy issues like Medicare for All, a Wealth Tax, a Green New Deal, cancelling student loan debt, providing universal free college, expanding Social Security, legalising marijuana at the federal level and erasing convictions, and raising the minimum wage to $15 an hour,” the letter read. “Now that Elizabeth has told us that her campaign is concluded, we know that she is considering how to best continue the fight for big, structural change. We respect that process and trust that she, as she always does, will do what is best to advance this movement.”

It continued: “We also understand and respect that many Warren supporters are still processing their feelings as well. We urge them to take care of themselves first and we stand ready to welcome them back into the fight when they are ready.”

The organisers said they ultimately made the decision to endorse Mr Sanders after Ms Warren dropped out of the race, writing: “We know that we won’t beat Donald Trump by simply talking about a return to business as usual.”

Ms Warren herself has declined to endorse anyone since dropping out of the race. If she were to choose Mr Sanders, her support could be seen as a boost of energy to his campaign after the former vice president raked in endorsements from previous Democratic presidential hopefuls just before last week’s vote.

If she chooses Mr Biden, that could potentially signal Mr Sanders’ campaign is dead in the water, according to some analysts.

In announcing the end of her campaign, Ms Warren said she would need time before potentially making an endorsement during a press conference with reporters outside of her home in Cambridge.