When Rep. Tulsi Gabbard (D-HI) was first elected to Congress in 2012 amid an ocean of positive press, the Iraq War veteran seemed like a sure thing for a 2020 presidential run. But her 2020 campaign has, so far, been a nearly complete nonstarter — averaging under 1 percent in national polls. That’s because the onetime progressive star has alienated many of her early supporters over her conservative stances on Islam and foreign wars. Gabbard initially excited the left because she was an outspoken economic progressive and a veteran who objected to American intervention abroad. She was also the first Hindu member of Congress. Nancy Pelosi called her an “emerging star”; MSNBC’s Rachel Maddow predicted she was “on the fast track to being very famous.” But in the following years, Gabbard staked out foreign policy positions that shocked her allies. She joined Republicans in demanding that President Obama use the term “radical Islam.” She was the member of Congress most willing to advocate for...