Carly Fiorina announced she is running Monday morning.
"I think I'm the best person for the job because I understand how economy actually works," Fiorina said during an interview on ABC's Good Morning America.
Although she is considered a longshot candidate, Fiorina has positioned herself as a foil to Hillary Clinton, often attacking the Democratic candidate for her track record as secretary of state and on social issues. The line of attack has been warmly received in the Republican Party, and it is likely that Fiorina will be the only female candidate in the Republican field.
The 2016 bid follows Fiorina's one, unsuccessful effort in 2010, when she ran against incumbent Democratic Sen. Barbara Boxer in California.
Fiorina is perhaps best known for serving as CEO of Hewlett-Packard in the late '90s and early 2000s. She has championed her record there, saying it shows she has the kind of executive experience needed to run the country. Her tenure there receives mixed reviews: Some at HP viewed her as a polarizing figure whose time as CEO was marked by layoffs and poor decisions; others have defended her record as a CEO trying to lead a company in desperate need of a transformation. She resigned from HP in 2005.