The 2020 Democratic presidential candidates are falling short of former President Barack Obama’s support among younger voters, raising a new hurdle to the party’s bid to dump President Trump.

A new poll of voters under 30 — millennials and Generation Z — have also abandoned younger candidates in the race, such as former South Bend, Indiana, Mayor Pete Buttigieg, favoring the oldest in the race, Sen. Bernie Sanders and former Vice President Joe Biden.

Forbes/Zogby poll

The Forbes Under 30 Poll, conducted by John Zogby Strategies, found that Sanders is the favorite of younger voters at 32%. Biden is second at 16%. Andrew Yang is at 8%. Buttigieg is last at 3%, tied with Sen. Amy Klobuchar and Rep. Tulsi Gabbard.

The analysis included a warning about the level of support younger voters have for the Democrats. “Any of these candidates is going to need to shore up young, undecided voters if he or she is going to beat Trump: Barack Obama carried 66% and 60% of young voters in 2008 and 2012, respectively,” said the Forbes report.

The survey conducted candidate matchups with Trump, and Sanders came close to Obama, beating Trump 58% to 34%.

It’s a pattern that played out in the 2016 election with Hillary Clinton, winning 55% of the younger vote.