In the 1988 campaign, Lee Atwater build a "Southern firewall" to ensure victory for George H.W. Bush even if he stumbled in Iowa and New Hampshire.
HRC is building her own firewall, as Patrick Healy and Amy Chozick report at
The New York Times:
In interviews, advisers said the campaign was increasingly devoting staff members and money to win the South Carolina primary on Feb. 27 while laying the groundwork to sweep Alabama, Arkansas, Georgia, Oklahoma, Tennessee, Texas and Virginia on March 1. Those Super Tuesday states are highlighted in red on maps in the offices of Mrs. Clinton’s senior aides in Brooklyn.
The eight primaries will deliver several hundred delegates for Mrs. Clinton, advisers believe, toward the goal of more than 2,200 needed to clinch the Democratic nomination. The campaign is barraging superdelegates in the South with requests for support — sometimes even jumping the gun by sending pledge forms prematurely — in hopes of adding scores of these party leaders who can bring their votes to the Clinton column at the Democratic National Convention.
The Southern firewall also includes Florida, Louisiana, Mississippi and North Carolina, which vote through mid-March. If Mrs. Clinton wins big in the Michigan and Ohio primaries that month, her advisers and supporters believe, the nomination will essentially be hers (though crossing the total delegate threshold takes time).
Her firewall is different from Bush's, of course, as she is relying heavily on African American and (especially in Texas and Florida) Hispanic Democrats.
Sanders has little support among these voters.