evidence: A winnowing field of Republican presidential candidates are working feverishly to close the polling gap between themselves and Donald Trump -- among them is former U.N. Ambassador Nikki Haley, whose support has steadily ticked up as an alternative to the former president. [...] Veteran Iowa strategist David Kochel said that Haley's emergence in the race as "the Trump alternative that has the most momentum" owes, in part, to the first three GOP debates. She gave performances that were widely well-received, including by likely primary voters who responded to a series of 538/Washington Post/Ipsos polls. (DeSantis got high marks in those post-debate polls, too.)