Why is the Iowa caucus so important? What to know about today's high-stakes vote

Republicans are in a fierce competition as they've crisscrossed all Iowa's 99 counties ahead of Monday's caucuses. Despite extensive efforts by several prominent Republicans to court Iowans, it appears they've fallen short as the state's caucuses approach, with former President Donald Trump maintaining a substantial lead over his rivals in the polls.

But as the first state to hold any nominating contests, Iowa acts as a litmus test for candidates vying for their party's nomination. And despite Trump's lead, Iowans have found themselves inundated with GOP candidates fervently pleading their cases.