The Iowa caucuses, which are the opening contest in the months-long Republican presidential primary process, begin at 8pm EST. Caucus participants will gather inside more than 1,500 schools, churches and community centres to debate their options, in some cases for hours, before casting secret ballots. On Sunday night, Trump implored his supporters to brave frigid temperatures for the vote and deliver him a decisive victory in the caucuses, saying their vote would help bring to Washington the retribution he has repeatedly promised if he returns to the White House. At a rally in Indianola, Trump…