Highlights from the 2024 campaign trail:Former President Donald Trump has a dominant lead in the final NBC News/Des Moines Register/Mediacom poll before Monday's caucuses, with former U.N. Ambassador Nikki Haley slightly ahead of Florida Gov. Ron DeSantis in a tight race for second.Trump hit out at businessman Vivek Ramaswamy on social media, stemming from Ramaswamy's recent insistence that support for Trump would be wasted because "the system" is lined up against him.Republican presidential hopefuls packed the day full of campaign events in Iowa, but they are still contending with low temperatures, wind and the heavy snow that forced the cancellation of some events Friday.The National Weather Service said Des Moines, Iowa, and surrounding areas remain under a winter weather advisory until midnight — and a wind chill warning through Monday's caucuses. Caucusgoers hunkering down at home will see more than $2.6 million in GOP TV ads through Jan. 15, according to AdImpact. Haley’s super PAC is spending the most, followed by one of DeSantis’ super PACs.