Elizabeth Warren has taken the lead and surpassed Joe Biden in a new Iowa poll

Democratic presidential candidate, Sen. Elizabeth Warren (D-MA) greets guests at the Polk County Democrats' Steak Fry on September 21, 2019 in Des Moines, Iowa.Getty Images/Scott Olsen

Sen. Elizabeth Warren of Massachusetts has been gaining ground in the race for the 2020 Democratic nomination and has even surpassed former Vice President Joe Biden, a new CNN/Des Moines Register/Mediacom poll of likely Iowa caucusgoers shows.

Warren has jumped to 22%, while Biden is polling at 20%, the poll shows. The survey has a margin of error of plus or minus 4.0 percentage points.

Strikingly, Warren's poll numbers have surged by seven percentage points since June, while Biden's have dipped by three percentage points.

The next-highest polling Democrats are Sen. Bernie Sanders of Vermont at 11% and South Bend Mayor Pete Buttigieg at 9%.

Democratic presidential candidate and former US Vice President Joe Biden addresses a crowd at a town hall event at Clinton College on August 29, 2019 in Rock Hill, South Carolina.Photo by Sean Rayford/Getty Images

Sen. Kamala Harris of California has the backing of 6% of the likely caucusgoers, while both Sens. Cory Booker and Amy Klobuchar have the support of 3%.

The businessman Andrew Yang, investor Tom Steyer, Rep. Tulsi Gabbard, and former Rep. Beto O'Rourke are each at 2%.

The poll also surveyed favorability ratings, which showed another surge for Warren - a whopping 75% now have a favorable view of her.

The poll showed that Warren's supporters are generally more enthusiastic than Biden's, with 32% of her supporters being "extremely enthusiastic" and just 22% for Biden.