The influential network associated with billionaire Charles Koch will throw its money and influence behind former South Caroline Gov. Nikki Haley in the Republican presidential primary, the group announced Tuesday. The decision could dramatically reshape the Republican field – roughly seven weeks before the Iowa caucuses – as Americans for Prosperity Action deploys its vast resources and standing army of conservative activists on behalf of the former South Carolina governor. The endorsement marks the latest sign that powerful Republican donors are coalescing behind the candidacy of the former US ambassador to the United Nations. She has seen prominent figures join...