Sen. Elizabeth Warren focused on stumping for Democratic Senate candidate Bruce Braley during a campaign stop in Iowa Sunday, but some liberal activists in the state that holds the first presidential caucus of 2016 made it clear they want her to run for the White House.

Warren, a popular Democratic campaign surrogate who focuses on economic inequality, campaigned for Braley in Iowa City and Des Moines. Her vigorous speech drew huge applause from several hundred supporters gathered at the Hotel Fort Des Moines Sunday afternoon.

Braley, a four-term congressman from Waterloo, is in a tight race against Republican Joni Ernst, a state senator and lieutenant colonel in the Iowa National Guard. The seat is viewed as crucial as Republicans seek to gain six seats and achieve a Senate majority.