File Photo of Joe Biden and Bernie Sanders. Photograph:( Agencies )
On Monday, Iowans take the first votes in the process that ultimately determines which Democrat will face US President Donald Trump in November.
The US presidential race begins in earnest Monday when Iowans take the first votes in the process that ultimately determines which Democrat will face incumbent Donald Trump in November.
Here are five questions on key aspects of a crowded race that remains wide open ahead of the February 3 Iowa caucuses.
Will septuagenarians rise?
As campaigning ramped up last year, Democrats thirsted for new voices and faces that would ensure the nation's growing diversity is better reflected in the presidential race.
More than two dozen candidates with various backgrounds, ethnicities, ages and orientations piled into the battle to see who challenges 73-year-old real estate magnate Trump.
But with Iowa looming, four white candidates in their seventies occupy the top spots in national polls.
Just this week, former New York mayor Michael Bloomberg, who turns 78 in February, climbed into fourth place in the Realclearpolitics polling average.
The billionaire businessman surpassed former Indiana mayor Pete Buttigieg, who at 38 is the youngest hopeful in the race.
Bloomberg entered the campaign late and is not contesting Iowa, where Buttigieg is in the top tier challenging rivals twice his age.
Radical party, or realist?
Who is best positioned to defeat Trump?
Consumed by this central question, Democratic voters must choose among favorites in a field sharply divided between radical progressives and more moderate realists.
It is currently the party's main quandary, underscored by The New York Times as it explained why, for the first time in its 169-year history, its editorial board broke with tradition to endorse not just a single candidate, but two: Warren, representing the more "radical" faction, and Amy Klobuchar, a 59-year-old senator in the "realistic" camp.
Biden and Buttigieg, like Klobuchar, take a more centrist approach while Sanders, a Democratic socialist seeking to win the nomination of a party he has never joined, calls for nothing less than political "revolution."
Four states, four winners?
With working-class voters, Midwest farmers, African-Americans or Hispanics seeing different strengths among each of the candidates, a different candidate could potentially win each of the first four early-voting states.
Iowa and New Hampshire (which votes second, on February 11) are largely rural and homogenous. Nevada (February 22) has a large Latino population, while in South Carolina (February 29), black voters represent a majority of the Democratic electorate.
Also see: Democratic Debate in Iowa
Given such a tight race, it is possible that no candidate arrives at the Democratic National Convention on July 13 with enough delegates in hand to claim victory.
Democrats and Republicans both use a complicated process involving pledged delegates proportioned according to primary and caucus results across the nation.
To carry the Democratic torch in the election, one must win a majority of the 3,979 delegates.
If no candidate has a majority, pledged delegates would become free to vote for someone else on the convention's second ballot if their candidate drops out.
Complicating matters, if the convention has no outright winner after the first ballot, more than 700 "superdelegates" -- party officials and insiders who are automatically made delegates -- would then be eligible to vote in selecting the nominee.
The Senate's Trump impeachment trial has had an unprecedented impact on the campaign, particularly in Iowa.
Four senators running for president -- Sanders, Warren, Klobuchar and low-polling Michael Bennet -- spent most of the last two weeks pinned to Washington, denied the personal contact with Iowa voters so vital before the caucuses.
Trump's impeachment by the House of Representatives on December 18 has not changed the political fault lines in an extremely divided country.
About nine in 10 Republicans support the president, and he is expected to be acquitted by the Senate's Republican majority.