Presidential hopeful Bernie Sanders is calling for young voters to fuel a political revolution. They’re not really listening, one reason Sanders is losing the Democratic race to former Vice President Joe Biden.

But Sanders has a bigger problem: Older voters are handily rejecting him. And older people are far more likely to vote than the 20- and 30-somethings Sanders considers his key constituency.

With Democratic primary elections now complete in 18 states, exit polls show a huge edge for Biden among voters 45 and over. Biden is getting 41% of the older vote, compared with just 18% for Sanders. The rest was split among Elizabeth Warren, Mike Bloomberg and others who have since dropped out of the race.

Sanders does much better among voters under 45, winning 47% of that group. Biden has won just 19%. But younger voters have accounted for just 36% of the vote so far, while older voters have cast 64% of the vote. That means Biden is winning the most populous group of voters – by a lot.

This vote split will change somewhat, following the recent departures of Warren and Bloomberg. And it will probably benefit Biden even more. Polling outfit Morning Consult found that Warren’s voters will migrate to Biden and Sanders more or less equally, with neither getting an outsized bump from her withdrawal. But Biden will get much of the Bloomberg vote, since both are moderates who appeal to similar voters. Bloomberg won about 13% of the vote before dropping out, and Warren, 10%.

Biden’s remarkable turnaround in the March 3 Super Tuesday contests have put him in the lead and made him the odds-on favorite to win the Democratic nomination, especially if he can win Michigan on March 10. The Sanders campaign has withered. But maybe that shouldn’t be surprising, given voter response to Sanders’ preferred policies.

[See the mammoth cost of Bernie Sanders’ big plans.]

Sanders’ biggest pitch is Medicare for all, a huge government program that would eliminate private insurance and provide health care for everybody. It makes sense that younger voters would favor this more than older voters. The young are obviously more idealistic and perhaps less concerned about the impracticalities Medicare for all would entail. Older voters are more pragmatic, and perhaps more wary of the massive disruption killing private insurance would cause. And anybody 65 or older already has access to Medicare. They may think, with some justification, that expanding it to everybody would jumble the whole program and interfere with their care.

Sanders wants to finance Medicare for all and many other social-welfare programs with higher taxes on the wealthy. And who are the wealthy? With the exception of those who inherit money, the wealthy are typically older workers later in their careers, close to their peak earning power. They’ve had time to save and invest. Some of Sanders’ tax hikes, such as the wealth tax, would only affect the superrich. But others, like a higher payroll tax to finance expanded Social Security benefits, would hit upper-middle income families. And 50-year-olds are much likelier to pay that new tax than 30-year-olds.