Gabbard, a delegate for Hawaii in the House of Representatives, told CNN in an interview set to air on Saturday night that she will formally announce her candidacy within the week.
"I have made a decision to run and will be making a formal announcement within the next week", Gabbard, a liberal 37-year-old Iraq War veteran as well as the first Hindu and first Samoan-American elected to the US Congress, told CNN.
Senator Elizabeth Warren has formed an exploratory committee for a presidential bid, and last week took a high-profile trip to the early voting state of Iowa. Bernie Sanders, are now weighing whether to run for president and are expected to announce their decision soon.
She had a run-in with Harris this week, accusing her of religious bigotry for her opposition to a nominee for federal judgeship because he belonged to a Catholic organisation called the Knights of Columbus.
Gabbard joins an increasingly crowded field of Democrats vying to be president.
Manafort accused of lying about sharing polling data with Russian
The filing did not indicate whether the polling information involved internal campaign data or when exactly it was provided. The US believes he is connected to Russian intelligence, but Mr Kilimnik, who is not in US custody, has denied those ties.
As one of our loyal readers, we ask you to be our partner. While her support for Sanders' economic message may turn off libertarians for obvious reasons, it's hard to imagine there being anyone in either major party primary who will be more critical of America's wasteful and seemingly endless post-9/11 wars. Gabbard would likely fight for attention in the race with other big names in the party, like former Vice President Joe Biden, Vermont Sen. "There are a lot of challenges that are facing the American people that I'm concerned about and that I want to help solve", she said, citing health care access and climate change among them.
Gabbard was criticized in 2016 for traveling to Syria and meeting with President Bashar Assad, who has been accused of war crimes. "I'm seriously thinking of how I can best be of service to our country", she told Concord Monitor News reporter Paul Steinhauser before meeting with Rockingham County Democrats.
Gabbard's spat with Hirono is just the latest incidence of her alienation from establishment Democrats.
Gabbard is so far left that she lost the support of a Hawaii teacher's union over her handling of Syria.
Gabbard, who is also the first Hindu member of Congress, is one of the first major candidates to directly declare a presidential candidacy.
Rania Batrice, who was a deputy campaign manager for Bernie Sanders in 2016 and is now a top aide to Gabbard, will be her campaign manager, CNN reported.