The open sniping between President Trump and the Bush family comes at the same time that veteran Democratic insider Donna Brazille is revealing her doubts about Hillary Clinton’s candidacy and the process by which she beat Bernie Sanders.

It’s not a mere coincidence. The dynasties at the top of the two major parties for the past quarter-century are under attack from within as never before. Trump ran as a rejection especially of George W. Bush in the 2016 Republican primaries and used Jeb Bush as a foil during the debates, riding that anti-establishment wave all the way to the White House.

Hillary Clinton was able to beat back a surprisingly strong primary challenge from Sanders, the septuagenarian socialist senator from Vermont who had never even appeared on the ballot as a Democrat before. But Sanders was running against Bill Clinton’s centrist Democratic Leadership Council legacy as much as his was a protest candidacy against Hillary.

Both outcomes have been second-guessed. Hillary’s defeat at the hands of Trump has some Democrats quietly questioning whether Sanders was right all along, even as they cheer her not-so-cathartic book tour. Republicans (and more than a few liberals) have begun to miss the virtues of both Presidents Bush after prolonged exposure to Trump’s vices.

Nevertheless, the underlying political conditions in both parties appear to be moving against the Bushes and Clintons. Look no further than Virginia, where no less of a Bush Republican than Ed Gillespie has taken a page out of Trump’s playbook to run a hard-nosed campaign in which culture war issues have been more prominent than his preferred technocratic policy solutions (though one could argue his campaign ads are also reminiscent of the work the late Lee Atwater did for George H.W. Bush).

It remains to be seen whether Gillespie will prevail in Virginia, as voting takes place on Tuesday and the polls are all over the place. He does, however, appear to be competing in a race originally assumed to be safely Democratic while his opponent Ralph Northam is facing backlash for presenting, even if by proxy, Gillespie voters as, in effect, a basket of deplorables.

The Democratic Party’s move in the Bernie wing’s direction may be even more pronounced. Democrats are increasingly rejecting the compromises with business and cultural conservatism that defined not only Bill Clinton’s presidency but also the candidate recruitment — by Chuck Schumer and Rahm Emanuel, no less — that helped the party retake Congress in 2006.

In 2006, Jim Webb was a netroots darling on the strength of his opposition to the Iraq war alone. By 2016, he was a culturally conservative pariah among Democrats.

If Sanders had more minority support last year, he might have beaten Clinton. Thus a platform of “Medicare for All” plus identity politics is enticing to many Democrats.

Brazile’s revelations about the coziness between Clinton and the Democratic National Committee feel like a shot across the bow, a warning that this is not the Clintons’ Democratic Party anymore.

“I don’t think the risk is so much that she’ll run again [in 2020],” said a Democratic strategist who requested anonymity to speak candidly about the Clintons. “But you do have to worry about her sucking all the oxygen out of the room before fresher faces can establish themselves.”

Ideology aside, there is a strong appetite in both parties for leaders who will take the fight to the other side. While that is more the Clintons’ style than the Bushes, both families are also seen in some corners as part of a bipartisan glad-handling establishment.

Trump would have seemed out of place among the former presidents at the recent hurricane relief concert (thus he appeared only by video) while we have seen the Clintons and Bushes pal around for years.

"The fight in both parties is not about policy," a Republican strategist recently told the Washington Examiner. "It's how we talk about the ‘them.' The tougher you are on the ‘them,' the better you are doing.”

The Democrats’ leftward movement on healthcare and social issues, combined with the hardening of GOP attitudes on immigration, suggest there might be more to it than that. But both parties are facing a shake-up that their elders and longtime leaders can no longer contain.