Sen. Elizabeth Warren jumped into the 2020 presidential campaign Monday, offering a message of economic populism as she became the best-known Democratic candidate yet to enter what is expected to be a crowded race.

Warren’s announcement that she was establishing an exploratory committee — the legal precursor to a run — came as other candidates, including several of her fellow senators, made final preparations for their own announcements, some of which are expected in days.

“America’s middle class is under attack,” the Massachusetts Democrat said in a four-minute, 30-second video emailed to supporters Monday. “How did we get here? Billionaires and big corporations decided they wanted more of the pie. And they enlisted politicians to cut them a bigger slice.”

Warren is one of more than a half-dozen senators expected to run for president, including Democrats Cory Booker (N.J.), Kamala D. Harris (Calif.), Sherrod Brown (Ohio), Amy Klobuchar (Minn) and Kirsten Gillibrand (N.Y.), as well as independent Bernie Sanders of Vermont, who shares Warren’s populist underpinnings.

Read more in the Washington Post.