Tran told the Los Angeles Times that she was motivated to run by Republican attempts to roll back the 2010 health care law.
“He was very callous and he did not vote for the needs of his constituents,” Tran said of Royce.
Tran came to the United States as a refugee in 1975 after the fall of Saigon and studied at Harvard while working as a janitor.
She then worked as an analyst on Wall Street before completing the Dartmouth-Brown medical program, according to the Orange County Register, and is part of a private practice there.
Tran’s entrance makes the her the second Democratic challenger alongside former chemistry professor Phil Janowicz, who backed Sen. Bernie Sanders in California’s primary last year. Tran volunteered for Hillary Clinton.
But Dave Gilliard, Royce’s political consultant, dismissed Tran’s entrance in the race.
“A single-issue candidate who lives and works miles from the district she seeks to represent is no match for Ed Royce, one of the most effective members of the House of Representatives,” Gilliard said.
Tran does not live in Royce’s district, but residency in the district is not required to run for Congress.
Though Royce won re-election last year by 14 points, his district was one of 23 Republican-held congressional districts that voted for Hillary Clinton last year, according to the liberal website the Daily Kos.
Royce, chairman of the House Foreign Affairs Committee, is among the Republican incumbents targeted by the Democratic Congressional Campaign Committee this cycle.