(CN) – Former vice president and 2020 presidential hopeful Joe Biden has solidified his lead over the field of candidates for the Democratic nomination, restoring double-digit increases over his closest competitors in a Tuesday poll.
The CNN/SSRS poll of 1,001 Democratic and Democratic-leaning registered voters found 29% support the former vice president, a 7-point gain for Biden from a June survey.
The poll, conducted August 15-18, found 15% of potential voters support Vermont Sen. Bernie Sanders – an Independent seeking the Democratic nomination – while 14% back Massachusetts Sen. Elizabeth Warren.
Warren and Sanders’ respective positions in the poll have remained largely unchanged in summer polling by CNN.
California Sen. Kamala Harris saw a 12-point decline in the CNN poll, dropping from 17% support from potential voters in June to 5% support in Tuesday’s poll.
Harris’ current position in the poll mirrors her initial post-Democratic debate level of support following a standout performance in which she challenged Biden on school busing integration and his collaboration with conservative senators from southern states.
More self-identified Democrats (31%) than independents (23%) said they support Biden, according to Tuesday’s poll.
Biden has more support from voters aged 45 and up (34%) than from voters younger than 45 (23%), the poll found.
Support for Biden from moderate and conservative voters (34%) also outweighs backing from liberals, who split support in a near three-way tie between Warren at 23% and Biden and Sanders at 22% each.
Among liberals, 53% said beating President Donald Trump in the 2020 election is more important than selecting a candidate who “shares your positions on major issues,” while 57% of moderate or conservative Democratic voters said the same.
Of Democratic and Democratic-leaning registered voters, 54% said beating Trump in the 2020 election is the top priority and 35% of them also support Biden, the poll found.
No other Democratic candidate registers close to 5% support among liberals, the poll found.
Democratic candidate Julian Castro, the only Latino in the crowded field of 2020 candidates, registered 2% support in the CNN/SSRS poll Tuesday, reaching the polling threshold set by the Democratic National Committee to qualify for the September primary debate.