Sen. Elizabeth Warren (D-MA), who announced the formation of an exploratory committee for a 2020 presidential bid a month ago, is expected to formally enter the contest at a coming event. "One month ago today, we launched this presidential exploratory committee to build a grassroots movement to level the playing field for working people," the Senator wrote in a Facebook post. "Since then, we’ve traveled to Iowa, New Hampshire, South Carolina, Puerto Rico, & heard from thousands of people all across the country. I’ll be making a BIG announcement about my 2020 plans on Saturday, February 9." The campaign said the location of the event will be announced this weekend. Since her entrance into the contest, Warren has helped shape the primary debate targeting billionaires and introducing a wealth tax that would impose a 2 percent tax on Americans with assets above $50 million and a 3 percent tax on those with more than $1 billion.

—Gideon Resnick