WASHINGTON, April 24 (Xinhua) -- Former U.S. Vice President Joe Biden, with strong support from older voters and African-Americans, leads a new poll of more than a dozen Democratic hopefuls for the party's 2020 presidential nomination.

Biden is supported by 26 percent of likely Democratic primary voters, followed by Senator Bernie Sanders with 15 percent, according to the Reuters/Ipsos poll released Wednesday. Both of them also enjoy the highest levels of name recognition among Democrats in the survey.

No other Democratic candidate registered the support of more than 7 percent of the respondents, the poll showed, noting that 21 percent of the electorate is still undecided.

Four out of ten African-Americans said they supported Biden, who was also backed by 32 percent of the respondents aged 55 and older.

Biden, aged 76, is expected to announce his candidacy with a video released on Thursday morning and then travel to Pittsburgh for a more formal event on Monday.

The poll, conducted online in English throughout the United States between April 17-23, surveyed 4,018 adults including 1,449 Democrats.