The US election isn't until November but the race for the White House officially kicks-off this week. Republicans in Iowa will be casting their votes for the party's nominee. Donald Trump is up against high profile rivals including his former UN ambassador Nikki Haley and Florida governor Ron Desantis. But the former president is still the overwhelming frontrunner for the nomination despite facing four sets of charges and a legal push to stop him from running in some states. If he does become the candidate, he'll likely face a re-match with Joe Biden whose campaign is grappling with concerns about his age and unpopularity.