A how-to guide to Monday’s Iowa Caucuses

Bernie Sanders has run the campaign he wants to run, noting, simply, “we have differences”.

Among the wide Republican field, recent polling suggests that businessman Mr Trump has a comfortable, though not certain, lead over his main rival, Texas Senator Mr Cruz. On the other hand, if the commitment of these political neophytes doesn’t extend to actually journeying out in the cold night and spending several hours caucusing in a classroom or barn, it will be Cruz who will get a boost.

Republicans vote by private ballot.

The weather will also be a factor.

“My prediction is that if, tomorrow night, there is a large voter turnout, we will win”.

The state is tailor-made for Ted Cruz, with lots of conservative evangelical voters. But it’s hard to see how he becomes the nominee – and begins to make up ground with minority voters – without winning Iowa.

Asked whether Rubio could win or come in second, his senior strategist Todd Harris laughingly responded with an obscenity and said the goal in Iowa is third, behind the flamboyant Trump and the highly organized Cruz.

Mr Trump joked with his supporters on Saturday, saying: “You’re from Iowa!”

A blizzard is bearing down on the upper Midwest, with at least some snow expected in parts of Iowa during Monday evening’s caucuses. A surge of voters from the centre that lifts Clinton and Marco Rubio, the front-runner among mainstream Republicans, may be the biggest surprise for the pollsters this year. As our colleague Steve Kornacki has noted, Barack Obama was either ahead or trailing in single digits in every SC poll at this same point in the “08 cycle”.

He has a strong appeal among Iowa’s religious community. Trump also holds the national betting lead, as aggregated by PredictWise.

That strategy might push him over the top and into first place. Hillary Clinton, stung by her third-place finish eight years ago, built a formidable get-out-the-vote operation.

Iowa offers only a small contingent of the delegates who will determine the nominees, but the game of expectations counts for far more than the electoral math in the state. The Iowa Poll, published by The Des Moines Register and Bloomberg, found former Secretary of State Hillary Clinton with 45 percent support to Sanders’ 42 percent.

New Hampshire voters frequently make up their minds in the final days of the contest – according to exit polls there in 2012, 46% of Republican voters said they made their decision in the last few days, as did 38% of Democratic voters in 2008 – so the results in polls right now are by no means the final word on the race.

This matters for Democrats. Democrats will gather at 1,100 locations and Republicans will gather at almost 900 locations across the state.

When it’s all said and done, the number of delegates will be given out. Sanders could be at a disadvantage here because his support has been heavily concentrated in college towns and urban areas, although the Sanders campaign has been trying to expand its reach to rural areas.

By late today, presidential hopefuls will learn whether the time, effort and money they poured into their campaigns have been rewarded with the kind of strong showing here that would lend huge momentum to their cause when the race shifts toward the next vote, in New Hampshire.