With the Iowa caucuses just over a year away, Democratic caucusgoers are most likely to say former Vice President Joe Biden is their pick for 2020.

A new poll from CNN, the Des Moines Register and Mediacom reveals 32 percent of likely caucusgoers say Biden is their first choice. He is followed by Vermont Sen. Bernie Sanders, with 19 percent support, Rep. Beto O'Rourke with 11 percent, Massachusetts Sen. Elizabeth Warren with 8 percent, and California Sen. Kamala Harris with 5 percent. Biden also has the highest favorability rating among likely Democratic caucusgoers, at 82 percent. An earlier CNN poll in October of Democratic voters nationwide also landed Biden on top.

Not only does Biden generate the most support among Democrats in Iowa — previous polls suggest the public thinks he has the best shot at defeating President Trump, who filed papers for reelection the day he took office last year. Mr. Trump has called Biden his "dream" opponent for 2020, but a July Politco/Morning Consult poll showed Biden beating Mr. Trump 46 percent to 35 percent in a hypothetical 2020 match-up.

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Taking the lead in early polling in Iowa doesn't always mean winning the caucuses, or making it all the way to the White House.

In August 2015, the Des Moines Register showed Hillary Clinton polling ahead of Sen. Bernie Sanders by 7 points. Clinton won the Iowa caucuses and the nomination of her party, but obviously lost in the general election. On the Republican side, in January 2015, the paper's polling showed Wisconsin Gov. Scott Walker leading the Republican pack, and he ended up dropping out of the race months before the Iowa caucuses. It was Texas Sen. Ted Cruz who won the caucuses, and he also bowed out of the race, making way for Mr. Trump.

In June 2011 ahead of the 2012 caucuses, Des Moines Register polling showed former Massachusetts Gov. Mitt Romney with a slight edge over Michele Bachmann. But a final count of the votes in 2012 showed Rick Santorum the victor in the Iowa caucuses. Santorum dropped out of the race months later. Romney did end up winning the GOP nomination but lost the presidential election to the sitting president, Barack obama.

In May 2007 ahead of the 2008 Iowa caucuses, it was John Edwards who held the lead in the Des Moines Register's polling. Then-Sen. Obama ultimately won the Iowa caucuses, and the White House. On the Republican side, in May 2007 it was Romney who had the edge in Des Moines Register polling. Other pollsters had now-Trump attorney Rudy Giuliani as the favorite. Former Arkansas Gov. Mike Huckabee won the Iowa caucuses among Republicans in 2008. But the late Sen. John McCain, not Huckabee, clinched the GOP nomination, only to lose to Obama.

Biden has yet to say whether he's running in 2020. He decided not to enter the race in 2016 and ultimately expressed some regret about that decision. In an October interview with "CBS This Morning," Biden said he isn't deciding whether he should run based on polling.

"I don't think about the polling data," Biden told "CBS This Morning" co-host Norah O'Donnell. "I think about whether or not I should run based on very private decisions relating to my family and the loss of my son and what I want to do with the rest of my life. But I don't think of it in terms of can I win, can I – will I lose. That's not part of the calculation."

Biden, despite his intense criticism of the president, doesn't think moving to impeach him is the right move for the Democratic Party.

"I think we should focus on all the terrible things that are happening now in terms of interest of the middle class people and working class people," Biden told "CBS This Morning."

The latest poll showing Biden leading among likely Democratic caucusgoers polled 455 registered voters with a margin of error of 4.6 percentage points.

The Iowa caucuses are set for February 2020.