With the second round of debates for Democratic hopefuls concluded, and with a week for 2020 candidates to make the rounds of TV interviews, the race for the Democratic nomination has started to tighten.

An August poll of likely voters in the New Hampshire primary, conducted by Suffolk University, in partnership with Boston Globe, shows former Vice President Joe Biden is still the front-runner. However, his lead, once projected to be in the double digits, has dwindled.

Biden polled at 21%, while Sen. Bernie Sanders (D-Vt.) trails by just four points with 17%. Both lead Sen. Elizabeth Warren (D-Mass), who claimed 14% in the poll. The results, when compared to the same poll issued in April of this year, show Sanders and Warren gaining ground after the debates.

Sen. Kamala Harris (D-Calif.), who took a few blows from upstart Rep. Tulsi Gabbard (D-Hi.) in last week’s debate, came in fourth place with 8%. Pete Buttigieg, Mayor of South Bend, Indiana, polled in fifth place with 6%.

Gabbard’s debate performance enabled her to effectively jump in the race, as she secured 3% in the poll. Gabbard will need to continue to perform at 2% or better in three additional polls, and she will need to grow her base of contributors to over 130,000, in order to secure a position in the next round of debates, to be held in Houston, beginning September 12.

Two candidates are notable for their poor showings in the poll, including Sen. Cory Booker (D-N.J.) and Rep. Beto O’Rourke (D-Texas), came in at 1% and 0%, respectively.

The poll was conducted August 1-4 and surveyed 500 Democratic voters likely to participate in the New Hampshire primary.