Sen. Bernie Sanders (I-Vt.) is increasing the size of his campaign staff and boosting state budgets in an effort to chip away at Hillary Clinton’s southern stronghold, Reuters is reporting.

Sanders’s campaign manager, Jeff Weaver, told the news service that the campaign rewrote its budgets last week to add more staff to states that will cast ballots on Super Tuesday.

A dozen states will hold votes on March 1 and award delegates on a proportional basis, rather than a winner-take-all system. Weaver said the campaign has calculated that it is worth competing hard in these states, even though Sanders may not perform as well as Clinton.

Clinton currently leads Sanders nationally by 25 points, according to RealClearPolitics average of polls.

Sanders is more competitive in the early voting states of Iowa and New Hampshire. But he but drops off sharply as the Democratic primary contest moves to the South.

Clinton has capitalized on strong debate performances and stands to gain as the election takes more of a focus on foreign policy.

“Eighty percent trust her most on national security,” Democratic pollster Tom Jensen told Reuters.