Democratic 2020 U.S. presidential candidate and former Vice President Joe Biden greets supporters following his speech at The Graduate Center of CUNY in New York, July 11, 2019. Carlo Allegri | Reuters

Joe Biden leads the 2020 Democratic presidential primary race, according to the first NBC News/Wall Street Journal poll of the contest. The former vice president draws the support of 26% of voters nationally who plan to vote in 2020 Democratic nominating contests, the survey released Thursday found. Sen. Elizabeth Warren, D-Mass., trails him at 19%. Sens. Kamala Harris, D-Calif., and Bernie Sanders, I-Vt., each get 13% of support, according to the poll. South Bend Mayor Pete Buttigieg rounds out the top five contenders at 7%. Former Rep. Beto O'Rourke and entrepreneur Andrew Yang both garner 2% of support, and no other candidate in the field of about two dozen draws more than 1%.

The survey largely squares with what recent polls have found about the contenders in the race to challenge President Donald Trump next year. While Biden jumped out to a more substantial lead in early polls, surveys suggest a tighter contest after the first Democratic debate last month introduced more voters to the field. Much can change before Democratic voters start choosing their nominee. The first-in-the-nation Iowa caucus sits about seven months away. Only 12% of respondents to the NBC/WSJ poll say they definitely made up their minds about who they will support next year. Asked about their second choices for president, 14% of respondents chose Harris. She was followed by Warren at 13% and Sanders at 12%. Meanwhile, 10% of respondents picked Biden as their second choice, and 8% chose Buttigieg.

Harris and Warren get strong marks after first debate

The survey was taken after the first Democratic debate in Miami, which appeared to reflect well on Harris and Warren. Nearly half — 47% — of Democratic primary voters who watched at least some of the debates or paid close attention to news coverage of them said Harris most impressed them. About a third responded that Warren impressed them most. Harris, one of three black candidates in the field, created the debate's most discussed moment when she targeted Biden's record on race and his stance on school busing policy. She told a story about getting bused to school in a newly integrated California school as a child. The former vice president comfortably leads the field among African-American Democratic primary voters, according to the NBC/WSJ poll. He garners 46% of support, trailed distantly by Harris at 17%. Among non-white primary voters, Biden draws 33% of support, followed by Harris at 16%, Sanders at 15% and Warren at 14%. Biden leads among primary voters who consider themselves moderate or conservative. Warren has an edge over Sanders among liberal respondents.

Do voters want big or small changes?

One core issue that will define the Democratic primary is whether voters want sweeping overhauls or incremental change. For example, Sanders and Warren have backed a single-payer "Medicare for All" system and massive student debt forgiveness. Biden and others have cautioned against Medicare for All or widespread debt cancellation, calling the plans too expensive. More than half, or 54%, of Democratic primary voters said they want a candidate who "proposes larger scale policies that cost more and might be harder to pass into law, but could bring major change" on issues such as health care, climate change, college affordability and economic opportunity. Meanwhile, 41% responded that they prefer a candidate who "proposes smaller scale policies that cost less and might be easier to pass into law, but will bring less change" on those issues.