Representative Tulsi Gabbard of Hawaii, who has remained in the race for the Democratic presidential nomination even as her bid has failed to gain much traction in polls, announced Friday that she would not seek a fifth term in Congress.

The announcement was likely to fuel speculation that Ms. Gabbard may be preparing for a third-party race for the White House, a prospect that has unnerved Democrats. Last Friday, Hillary Clinton suggested that Republicans were “grooming” her for such a bid, though Ms. Gabbard has denied any such plans.

In a statement, Ms. Gabbard cited her desire to become president as the reason for not seeking re-election to her current office, telling her constituents that she would “humbly ask you for your support for my candidacy for president of the United States.”

Ms. Gabbard, whose noninterventionist views have set her apart from her party, said she was the best person to lead the nation at a time when “we may be sucked into another even more disastrous war in the Middle East, and tensions with other nuclear powers are escalating.”