Go back to the second half of the second term of the Bush Administration.

Really in 2005, but then after 2006, there was wide spread disagreement between the base of the party and President Bush on a host of issues. Bush’s appointment of Harriet Miers and immigration reform had begun it. But into 2007, the war effort was a subject of concern, TARP was a point of dispute, the GM bailout was a vocal point of contention. Republicans in Congress were fractured over what to do. Leadership was going one way and much of the rest of the party was going the other way.

A shake up was under way within the party.

What is remarkable about the Democrats is how top-down the party has become to the point of casting aside any leader who dissents with the White House. The outrage over Chuck Schumer and the Iran deal is just the latest, but it is significant. Democrats are loudly denouncing Schumer for rejecting a bad deal.

A lot of people may nod their heads and think that toeing the party line and keeping unity will make things work out better for the Democrats than it worked out for the GOP in 2008, but I don’t actually think so. And I don’t think so because of the same reason on the right — the heir apparent is not running.

The fatal mistake George Bush made in 2008 was not having Dick Cheney run for the Presidency. Without Cheney, the party was forced to go back to 2000 and refight the McCain fights all over again. All the long settled issues came spilling back out. Party unity turned to discord. But the discord did not burst forth like from a dam. It was already there.

Cheney, not running, prevented the GOP from having a referendum on the legacy of George W. Bush. But the various elements split within camps. Each had bits and pieces of the Bush legacy they were willing to uphold and we had a smorgasbord of candidates and Bush related doctrines to choose from.

The Democrats now are waiting for the dam to burst. The White House’s heir is not running. Hillary Clinton comes close, but she separated herself from the White House after the first term. She’s also a Clinton willing to run on a Clinton legacy, not an Obama legacy. Her rhetoric and tone is already about restoring the Clinton dynasty.

Schumer’s rejection of the Iranian deal signals a Democratic divide, but let’s not kid ourselves. The divisions have been building up pressure for a while. President Obama is on his way out, he’s legacy building for himself, not the party, and resentment is building. We get trickles of this occasionally with recent reports that Democrats in private thought Obama rude. We’re getting more trickles with Schumer. The dam will burst.

When it bursts, instead of the slow but steady tide of GOP discord post-2006, there will be no one person to rally around as a referendum on Obama’s legacy. Just as Cheney not running failed to consolidate the Bush forces behind one camp, Biden not running will do the same for the Democrats.

They are then going to have to go back to 2008 and fight all over again. Someone will stand up to be the President’s surrogate and it will not be Hillary Clinton. Sixty-five percent of voters say they would not vote for Obama again. So Clinton has no reason to uphold Obama’s legacy. And say what you will as a partisan, but Bush was far more humble than Obama. Obama will not as readily as Bush be willing to see his legacy fracture.

Ultimately, this leads to more and more litmus tests of what it will mean to be an authentic Democrat. It will lead to a Democrat version of the Tea Party group far angrier than the one on the right. Occupy Wall Street will look like a piker compared to what is coming.

Within the Republican Party, it is far easier to be pro-abortion and pro-gay marriage and pro-gun regulation than it is to be pro-life, pro-tradition, and pro-gun in the Democratic Party. It is easier in the GOP to raise taxes than it is in the Democratic Party to cut spending. It is easier in the GOP to be against intervention than it is in the Democratic Party to call for a robust military. It is easier in the GOP to oppose Israel than it is in the Democratic Party to support Israel.

It will only get worse for Democrats. It will only get worse because a party at odds with their own President, but that still yields too him, will, when the dam bursts, overplay its strong men and strong arms to impose silence within. That will hurt them and it will also be very, very fun to watch.