The latest news and updates on the Iowa caucuses:Iowa Republicans will caucus today at 7 p.m. CT, officially kicking off the party's presidential nominating process.Former President Donald Trump holds a clear polling lead, with the final NBC News/Des Moines Register/Mediacom Iowa poll showing him with the support of 48% of likely GOP caucusgoers. He's followed by former U.N. Ambassador Nikki Haley with 20%, Florida Gov. Ron DeSantis with 16% and entrepreneur Vivek Ramaswamy with 8%. The campaigns and their supporters will battle subzero temperatures this evening. The National Weather Service is forecasting life-threatening cold conditions across Iowa, with wind chill values dropping as low as minus 35 degrees Fahrenheit.How the frigid weather affects turnout and what Trump's margin of likely victory will be are among the storylines to watch tonight.Republicans select their candidate by a simple secret-ballot vote, unlike the Democratic shuffling from one corner of a caucus site to the other. Here's how tonight's caucuses will work.