AP Photo/Charlie Neibergall
- Former President Donald Trump is poised to win big in the Iowa caucuses on Monday.
- The final pre-caucus NBC News/Des Moines Register/Mediacom Iowa poll shows Trump ahead of Haley 48%-20%.
- Trump's robust support among first-time and evangelical voters is far ahead of his 2016 standing.
Former President Donald Trump has long boasted enviable leads over his GOP challengers in polling for the Iowa caucuses, but his appeal with first-time caucusgoers and evangelical voters has put him in a class by himself a day before voting begins.