Lisa Desjardins:

Shaking hands in neighboring South Carolina was Senator Elizabeth Warren of Massachusetts. Absentee voting is already under way there. Warren lunched in Charleston with hip-hop artist Benny Starr.

The map is quickly expanding. Warren and Sanders started the day in the East, and Sanders plans to be in Texas, a big Super Tuesday state, tonight. But most 2020 hopefuls are farther west in Nevada. Today, the next state to decide drew an all-star lineup of former South Bend, Indiana, Mayor Pete Buttigieg, Minnesota Senator Amy Klobuchar, former Vice President Biden and billionaire activist Tom Steyer.

Buttigieg is hoping to maintain the momentum he got from the Iowa caucuses, when he narrowly edged out Sanders, and in New Hampshire, when he trailed just behind in second.

In Las Vegas, Klobuchar criticized ideas for government-run health care by Sanders and Warren as too far left.