Backgrounder: Key players in 2016 U.S. presidential race

So far in this U.S. presidential election cycle, there are 11 Republicans competing for the party's presidential nominee, while the Democratic field is much smaller with only three candidates. Here's a look at key Republican and Democratic contenders in this year's presidential race.

Key Republican candidates:

DONALD TRUMP -- For the past six months, the New York billionaire developer and reality TV celebrity has been dominating the crowded Republican field with no apparent match, at least according to polls.

Appealing to disaffected Republicans across the board, Trump embraced controversial positions that would otherwise end candidacy for other establishment candidates.

Son of Fred Trump, a wealthy real estate mogul, Donald Trump's brash personality and wealth had for long made him one of the most well-known figures in the country.

TED CRUZ -- A darling to the conservative Tea party, Cruz won his election to the U.S. Senate in 2012. Since his arrival in Washington, D.C., Cruz has been a vocal critic of both U.S. President Barack Obama as well as Republican leaders.

While attacking Obama on almost all issues had become a routine for Republicans in the past seven years, Cruz stands out for his equally harsh criticism against GOP leaders for what he calls their willingness to compromise when dealing with the Obama administration.

He became a national political figure in October 2013, when his opposition to Obama's 2010 healthcare law led to a partial government shutdown.

MARCO RUBIO -- A Cuban-American native of Miami, Florida, Rubio won his Senate election in 2010 and since then has established himself as a leading voice for the new generation of the Republican Party.

After the constant dominance of political outsider Trump and recent rise of Cruz, Rubio is now regarded a viable candidate for party elites and leadership.

However, Rubio's past record on a sweeping immigration bill that granted legal status threatens to drive away conservatives in the party.

JEB BUSH -- Once regarded the front-runner of the Republican field, former Florida Governor Jeb Bush's favorability numbers with Republican primary voters has tanked since last July despite his formidable campaign war chest and solid support within the party establishment.

The son of former President George H.W. Bush and the brother of former President George W. Bush, Jeb Bush also becomes a target of anti-politician sentiment of this election cycle.

BEN CARSON -- Retired neurosurgeon Ben Carson is the only African-American candidate in both parties in this year's election cycle. He gained national attention in 2013 after his speech at the National Prayer breakfast, in which he spoke bluntly about healthcare.

Being a stark comparison to Donald Trump, the mild-speaking retired neurosurgeon once gained seemingly unstoppable momentum last August by supports from conservatives looking for Trump's alternative.

However, his polling number plummeted after the Paris terrorist attacks due to doubts about his foreign policy knowledge.

Key Democratic candidates:

HILLARY CLINTON -- A former first lady, Hillary Clinton served as Obama's top diplomat from 2009 to 2013 after her loss in the 2008 Democratic primary to Obama.

Before the 2008 election, Clinton also served as New York senator and her ties to the Wall Street sometimes become a bit of fodder for her critics.

During this election cycle, in the face of surging support for Bernie Sanders in the Democratic Party, Clinton seeks to portray herself as a progressive that can make progress and work with a Republican-controlled Congress.

Though showing her support for Obama, who still enjoys large popularity among Democrats, Clinton has taken positions at odds with Obama on trade, the Keystone pipeline, etc.

BERNIE SANDERS -- Once being regarded as a long shot, Vermont Senator Bernie Sanders now poses real threat to Hillary Clinton's race to the White House, especially in Iowa and New Hampshire, the two states which hold the first two primary elections.

A native from Brooklyn, New York, Sanders was elected as mayor of Burlington, Vermont and won his Senate election in 2006. If elected, he would be the first Jewish president of the country.

The majority of his support in this election cycle comes from the liberal wing of the Democratic Party, and his rallies can attract thousands of young people to attend.

According to the final poll before the Iowa caucuses by the Des Moines Register/Bloomberg Politics, he is now trailing Clinton in Iowa by three points. Enditem