NEW YORK (AP) — Americans for Prosperity, the political arm of the powerful Koch network, formally endorsed Nikki Haley's presidential campaign on Tuesday, promising to commit its nationwide army of activists — and virtually unlimited funds — to helping Haley defeat former President Donald Trump in the GOP primary contest.

"AFP Action is proud to throw our full support behind Nikki Haley, who offers America the opportunity to turn the page on the current political era, to win the Republican primary and defeat Joe Biden next November," AFP president and CEO Emily Seidel wrote in a memo announci...