Biden, Sanders, Warren support dips in new poll

Top-tier candidates, including former Vice President Joe BidenJoe BidenPoll: Support for Sanders among college students reaches highest level since April Obama has taken active interest in Biden's campaign: report The Hill's Morning Report — Trump and the new Israel-'squad' controversy MORE and Sen. Bernie SandersBernie SandersPoll: Support for Sanders among college students reaches highest level since April The Hill's Morning Report — Trump and the new Israel-'squad' controversy Native American advocates question 2020 Democrats' commitment MORE, saw a dip in support over the past two weeks while several lower-tier candidates saw a slight uptick in their numbers, according to the latest Hill-HarrisX poll released on Wednesday.

The survey showed that 31 percent of likely Democratic primary voters back Biden, marking a 3 point drop from an identical poll conducted two weeks ago.

It also found a drop in support for Sanders and Sen. Elizabeth WarrenElizabeth Ann WarrenWarren unveils Native American policy plan Poll: Support for Sanders among college students reaches highest level since April Obama has taken active interest in Biden's campaign: report MORE (D-Mass.), the only other two candidates in double figures in the poll.

Sanders’s support dipped 4 points to 16 percent, while Warren’s support dropped 2 points to 10 percent.

Sen. Kamala HarrisKamala Devi HarrisPoll: Support for Sanders among college students reaches highest level since April Native American advocates question 2020 Democrats' commitment Fox News poll shows Trump losing to Biden, Warren, Sanders and Harris MORE (D-Calif.) retained her spot in fourth place but her 7 percent support is a decrease of 2 points since the July 29 poll. South Bend, Ind., Mayor Pete ButtigiegPeter (Pete) Paul ButtigiegPoll: Support for Sanders among college students reaches highest level since April Native American advocates question 2020 Democrats' commitment Hillicon Valley: Deepfakes pose 2020 test for media | States beg Congress for more election security funds | Experts worry campaigns falling short on cybersecurity | Trump officials urge reauthorization of NSA surveillance program MORE rounded out the top five with 4 percent, a 1 point dip over the past two weeks.

Former Texas congressman Beto O’Rourke, meanwhile, held onto to sixth place with 4 percent support, which is unchanged from two weeks ago.

The number of undecided voters ticked back up to 10 percent, after briefly dropping to 8 percent.

A handful of lower-tier candidates received a slight boost. 

Gov. Steve BullockSteve BullockBullock mocks Trump with online tool to determine if Greenland is for sale CNN to host de Blasio, Bullock town halls Native American advocates question 2020 Democrats' commitment MORE (D-Mont.), former San Antonio Mayor Julián Castro (D), and Sen. Amy KlobucharAmy Jean KlobucharNative American advocates question 2020 Democrats' commitment Biden, Sanders, Warren support dips in new poll 2020 Democrats release joint statement ahead of Trump's New Hampshire rally MORE (D-Minn.) all ticked up one point to two percent. Best-selling author Marianne WilliamsonMarianne WilliamsonNative American advocates question 2020 Democrats' commitment Biden, Sanders, Warren support dips in new poll 2020 Democrats release joint statement ahead of Trump's New Hampshire rally MORE, who had a breakout moment during the second round of Democratic debates, saw a two-point jump to 2 percent. 

The latest poll comes as a number of 2020 White House contenders make the rounds in Iowa to make their case to caucus goers.

Though the Iowa caucuses are still six months away, virtually every candidate has made an appearance at the Iowa State Fair, which is considered an essential campaign stop for presidential hopefuls on both sides of the aisle.

Many of the candidates are also scrambling to qualify for the next round of Democratic primary debates in September.

The Hill-HarrisX poll was conducted among 451 Democratic and Democratic-leaning independent voters with a margin of error of plus or minus 4.6 percentage points.

—Tess Bonn