"I was six years old when a presidential candidate came to the California Democratic convention and said it's time to pass the torch to a new generation of Americans," said California Democratic Congressman Eric Swalwell, 38, on the second night of the Democratic debate for the primaries.

"He was right when he said that 32 years ago. He is still right today," Swalwell continued.

The young candidate underlined with his argument a reality that would become palpable in the conclusion of the debate: perhaps Joe Biden's charm is over.

The former vice president represents a political generation that seems to no longer have a place in the United States, where bipartisanship has been actively undermined by phenomena such as Donald Trump and by cultural changes driven antagonistically by his Administration.

"Bernie and Biden were largely living off of inertia," said Colin Strother, a veteran Democratic strategist to Politico. "Now voters are becoming aware that other candidates have a lot of other things to offer."

At first, the Democratic primaries were somewhat predictable: high diversity of candidates, early announcements, and the return of Senator Sanders to the race.

We knew from the beginning that, before a government like Donald Trump, anyone would dare to launch a campaign for the presidency.

The result was more than 20 candidates, among Asian Americans, Hispanics, African-Americans and whites, senators, members of Congress, governors, authors, and entrepreneurs and, finally, a former vice president.

At the time of the first Democratic debate on Wednesday, the polls gave Biden the lead among the Democratic candidates with an approximate 41.5% approval.

By the end of the second debate, the polls gave the former vice president an approval of 31.5%, while candidates such as California Senator Kamala Harris saw their rates double.

In fact, according to a survey by Five Thirty-Eight and Morning Consult, Harris and Senator Elizabeth Warren replaced Sanders and Biden's positions of advantage, respectively.

The matter seems to go beyond the tail of the feminine revolution of recent years; it seems instead to indicate a turn from the political symbol - Biden, Sanders - towards the content and the proposal itself.

Beyond the Harris-Biden confrontation over segregation - an argument that took the vice president by surprise and gave Harris center stage - the rapport de force between the two candidates exemplified the need to put reality and history above the traditional political system, especially if the unshakable goal is to defeat Donald Trump.