The race for the White House starts in earnest this week, as candidates try to win voters over during a four-week sprint to the Iowa caucuses.

For the Democrats the US presidential election is basically a two-horse race. Senator Bernie Sanders, a Vermont independent, hopes an upset in Iowa and a victory in the New Hampshire primary a week later will dent the apparent inevitability of front-runner Hillary Clinton. Wins in the first two states for the former first lady, New York senator and secretary of state would all but cement her place on her party's ticket.

There is no such clarity in the Republican race. Despite shedding five candidates before New Year's Day, this contest is an unpredictable mix of a dozen hopefuls with vastly different visions for the party and the country. While Texas Senator Ted Cruz has edged ahead in preference polls of Iowa voters in recent weeks, nationally he still trails the unquestioned political star of 2015, Donald Trump. The big question is: are the crowds at his rallies likely voters, or merely fans entertained by the outrageous sideshow? Could Jeb Bush, Marco Rubio, John Kasich or Chris Christie emerge as the clear alternative?

One thing is for sure, with nearly a year to go until the presidential elections, the candidates on both sides will be pulling out all the stops, making a lot of heartfelt speeches, kissing a lot of babies, and appearing in a lot more entertaining photos – like these.

US elections 2016
A variety of Donald Trump's expressions from stops along the US Republican presidential candidate's elections campaign trailReuters/Getty Images
US elections 2016
19 December 2015: Hillary Clinton gives a thumbs-up to supporters in the crowd as Senator Bernie Sanders and former Governor Martin O'Malley shake hands with moderators Martha Raddatz and David Muir at the end of the Democratic presidential candidates debate in Manchester, New HampshireBrian Snyder/Reuters
US elections 2016
4 December 2015: Republican presidential candidate Donald Trump gestures as if he is sleeping while talking about his opponent Jeb Bush during a Trump for President campaign rally in Raleigh, North CarolinaJonathan Drake/Reuters
US elections 2016
10 November 2015: Democratic presidential candidate Hillary Clinton listens to a question from the audience during a veterans discussion in Derry, New HampshireBrian Snyder/Reuters
News photos of the year 2015
19 August 2015: Republican presidential candidate Donald Trump hugs a US flag as he takes the stage for a campaign town hall meeting in Derry, New HampshireBrian Snyder/Reuters
US elections 2016
4 January 2016: Audience member Robin Roy reacts as Republican presidential candidate Donald Trump greets her at a campaign rally in Lowell, MassachusettsBrian Snyder/Reuters
US elections 2016
21 September 2015: Republican presidential candidate and former Florida Governor Jeb Bush shows off a Reagan/Bush '84 T-shirt in MiamiJoe Radele/Getty Images
US elections 2016
30 June 2015: New Jersey Governor Chris Christie gets a kiss from a supporter after he formally announced his campaign for the 2016 Republican presidential nomination at Livingston High School in New JerseyBrendan McDermid/Reuters
US elections 2016
2 December 2015: Donald Trump autographs the chest of a woman at his campaign rally in Manassas, VirginiaGary Cameron/Reuters
US elections 2016
24 October 2015: Democratic presidential candidate Hillary Clinton is introduced at a fundraising dinner in Des Moines, IowaScott Olson/Getty Images
US elections 2016
23 December 2015: Rapper Killer Mike, left, and State Representative La Shawn Ford, right, listen as Democratic presidential candidate Senator Bernie Sanders speaks during a meeting with local activists and community members in Chicago, IllinoisJoshua Lott/Getty Images
US elections 2016
15 July 2015: Republican presidential candidate New Jersey Governor Chris Christie holds four-month-old Arlea Giovanna during a campaign stop in Annapolis, MarylandMark Wilson/Getty Images
US elections 2016
15 August 2015: Hillary Clinton greets Louie Dixon as she campaigns at the Iowa State Fair in Des MoinesJim Young/Reuters
US elections 2016
21 August 2015: Republican presidential candidate Donald Trump greets supporters after his rally at Ladd-Peebles Stadium in Mobile, Alabama. The Trump campaign moved the rally to a larger stadium to accommodate demandMark Wallheiser/Getty Images
US elections 2016
7 September 2015: Democratic presidential candidate Senator Bernie Sanders holds part of a sign with Whitney Adair, 7, before walking in a Labour Day Parade in Milford, New HampshireMary Schwalm/Reuters
US elections 2016
15 October 2015: Maria Anita Monsivaiz shows off an image of Hillary Clinton cut into her hair at a "Latinos for Hillary" rally in San Antonio, TexasDarren Abate/Reuters
US elections 2016
3 October 2015: Democratic presidential candidate Hillary Clinton points as she takes the stage before speaking to supporters at the Human Rights Campaign Breakfast in Washington, DCJoshua Roberts/Reuters
US elections 2016
27 June 2015: Donald Trump stands in front of a statue of John Wayne during a campaign event at the museum and birthplace of the actor while campaigning for the 2016 Republican presidential nomination in Winterset, IowaBrian Frank/Reuters
US elections 2016
13 April 2015: Senator Marco Rubio autographs a magazine with his picture on the cover after he announced his bid for the Republican nomination in Miami, FloridaCarlo Allegri/Reuters
US elections 2016
11 December 2015: Republican presidential candidate Donald Trump meets supporters after speaking at a campaign rally at the Iowa State Fairgrounds in Des MoinesScott Morgan/Reuters
US elections 2016
24 November 2015: Republican presidential candidate Donald Trump brings lookalike supporter Terry Silliman on stage during a rally in Myrtle Beach, South CarolinaRandall Hill /Reuters
US elections 2016
Twins Dante and Georgie Cicerone, 15, dress up as Republican presidential candidate Donald Trump as they attend a rally in Las Vegas, NevadaMike Blake/Reuters
US elections 2016
9 November 2015: A Donald Trump fan holds a pumpkin painted in the likeness of the outspoken Republican candidate as he waits to get into a campaign event in Springfield, IllinoisJim Young/Reuters
US elections 2016
4 January 2016: A supporter holds up The Trump Colouring Book at a campaign rally with the Republican presidential candidate in Lowell, MassachusettsBrian Snyder/Reuters
US elections 2016
4 January 2016: Marion Emslie waits for Republican presidential candidate Donald Trump at a campaign rally in Lowell, MassachusettsBrian Snyder/Reuters
US elections 2016
9 November 2015: A supporter of Republican presidential candidate Donald Trump attends a campaign event in Springfield, IllinoisJim Young/Reuters
US elections 2016
14 December 2015: A supporter wears a Trump T-shirt and badge as he attends a rally for the Republican presidential candidate in Las Vegas, NevadaMike Blake/Reuters
US elections 2016
21 December 2015: An attendee wears a "gun rights" badge on his shirt while waiting for Republican presidential candidate Donald Trump to address the crowd during a campaign rally in Grand Rapids, MichiganRebecca Cook/Reuters
US elections 2016
1 December 2016: Skywriting over the 127th Rose Parade makes a reference to Republican presidential candidate Donald Trump, in Pasadena, CaliforniaDavid McNew/Reuters
US elections 2016
11 December 2015: People take part in an anti-Trump, pro-immigration protest outside the Plaza Hotel in New York, where Republican presidential candidate Donald Trump was speakingBrendan McDermid/Reuters
US elections 2016
28 October 2015: Students and protesters gather at the "Free Speech Zone" at the University of Colorado as candidates gather before the Republican presidential candidates debateEvan Semon/Reuters
US elections 2016
12 October 2015: Demonstrators hold up a piñata of Republican presidential candidate Donald Trump during a protest outside Trump Tower in Chicago, IllinoisScott Olson/Getty Images
US elections 2016
10 October 2015: A protester opposed to Donald Trump's stance on immigration clashes with his supporters at a rally in Norcross, GeorgiaTami Chappell /Reuters
US elections 2016
13 July 2015: A protester holds up a sign before Wisconsin Governor Scott Walker's formal announcement of his campaign for the 2016 Republican presidential nomination in Waukesha, WisconsinDarren Hauck/Reuters
US elections 2016
20 November 2015: Democratic presidential candidate Vermin Supreme arrives to file his declaration of candidacy to appear on the primary election ballot in Concord, New HampshireBrian Snyder/Reuters