Washington: Hawaii congresswoman Tulsi Gabbard is suspending her presidential campaign, ending a long-shot effort that saw her feuding with Hillary Clinton and raising fears among Democrats that she would mount a third-party 2020 bid.

She is offering her full support to former vice-president Joe Biden. She made the announcement by email on Thursday.

Tulsi Gabbard has suspended her campaign for the Democratic presidential nomination. Credit:AP

"I feel that the best way I can be of service at this time is to continue to work for the health and wellbeing of the people of Hawaii and our country in Congress, and to stand ready to serve in uniform should the Hawaii National Guard be activated," she said.

During her candidacy, Gabbard appeared often on Fox News Channel and angered fellow Democrats by voting "present" on the articles of impeachment against President Donald Trump. In October, she announced she wouldn't be seeking reelection to her congressional seat, instead focusing on her presidential bid.