Sen. Kamala Harris (D-Calif.) and former tech entrepreneur Andrew Yang have been climbing in the Democratic presidential race, while the three front-runners - former Vice President Joe Biden, Sen. Elizabeth Warren (D-Mass.), and Sen. Bernie Sanders (I-Vt.) - have seen a slight dip though they remain ahead, according to a Hill-HarrisX poll released on Wednesday.

The survey, which has a margin of error of plus or minus 4.5 percentage points, shows Harris up three percentage points with 7 percent support among Democratic and independent registered voters.

This marks a boost for Harris, who has been in a slump in recent months. Following her breakout performance during the first Democratic debate in July, Harris surged past Warren to rank third in an identical survey conducted June 29-30, garnering as much as as 11 percent. But the California senator has since struggled to reach the double-digits.

The poll also shows Yang gaining ground on top-tier White House contenders. The former tech entrepreneur ticked up to his highest mark in the survey yet at 5 percent.

Top-tier candidates, including Biden, Sanders and Warren, all saw a slight dip. Biden slipped three percentage points to 27 percent, while Sanders dropped 2 points to 15 percent. Warren, meanwhile, dipped to 12 percent, which marked a 2-point decrease.

HarrisX researchers surveyed 454 registered Democrats and independents voters between September 7 and 8.

The survey comes as 10 Democratic presidential hopefuls prepare to take the stage Thursday night in Houston for the next round of Democratic debates.

Unlike the first two debates the upcoming debate will not be split into two nights, marking the first time all of the candidates will be together on the debate stage.

-Tess Bonn