MANCHESTER, N.H. —The morning after the first general election debate of the 2016 campaign, former Gov. John H. Sununu on Tuesday came full circle, formally endorsing Donald Trump for president. Sununu, who is also a former White House Chief of Staff and former New Hampshire Republican Party chairman, was among Trump’s harshest critics during the first-in-the-nation presidential primary campaign. But in a statement released by the Trump campaign, Sununu said: “Donald Trump is the only candidate in this race who can bring bold change to Washington, D.C. I support the Trump-Pence ticket for their pro-growth agenda and commitment to protecting...