Over the weekend, the "Cromnibus" budget was passed by a coalition that included the GOP leadership and the Obama White House. Neither conservative Republicans nor liberal Democrats were happy with what was in it. So why is it that the conservatives are feeling bitter and betrayed, while the liberals seem positively elated, despite the fact that they both lost?

We don't need to work too hard to understand the conservatives' reaction. The budget doesn't stop President Barack Obama's executive actions on immigration, and Republican leaders decided not to force another government shutdown in a vain attempt to do so. As usual, the conservatives are convinced that John Boehner and Mitch McConnell are wimps who do nothing more than bide their time between capitulations.

But what explains the liberal reaction? For the first time in this presidency, liberal Democrats feel as though something like a coherent bloc, outside of and sometimes in opposition to the White House, is beginning to form. Animated by a new sense of purpose, they're experiencing the flush of hope.

This is happening not just because the Obama presidency is entering its final phase-when the Democratic Party's future will be debated and determined-but also because complete control of Congress means that legislation is no longer much of an issue, apart from regularly scheduled crises on the budget and debt ceiling. In the past, liberals have raised objections to parts of Democratic bills-as they did when demanding the inclusion of a public option in the Affordable Care Act-but everyone knew they would come around in the end and join with other Democrats. Because they believe in governing and, as liberals are wont to do, prefer a compromise that gets something to a principled stand that gets nothing, they weren't in a position to make threats. Since they were with all the other Democrats on all the key fights, they weren't able to coalesce into a distinct political force.

That might be happening now, particularly since anything that the administration does from this point forward will be on its own; there won't be any more big liberal initiatives enacted through legislation. For the left, that's liberating.

Even though this budget passed, and did so with the inclusion of a provision literally written by Citigroup lobbyists to allow more risky financial trades with taxpayer-guaranteed funds, liberals are seeing a victory. Just the fact that the provision became controversial and gave Elizabeth Warren the opportunity to denounce it on television, invoke Teddy Roosevelt's trust-busting, and call for the breakup of the big banks, was enough to make them cheer.

That's particularly true of those who still hope that Warren will run for president in 2016.

"This is Elizabeth Warren's moment," said Ben Wikler of MoveOn to Politico this weekend

; his group has pledged to spend $1 million encouraging Warren to run. Three hundred former Obama campaign workers signed an open letter last week urging Warren to enter the race. In a piece titled "Elizabeth Warren has arrived and so have we," Kerry Eleveld wrote at Daily Kos: "even if Warren doesn't run, the energy that exists to draft her is still worth having because it gives her power, it gives her relevance, and it can absolutely be used to moderate the forces on the right." It's almost impossible to overstate how central Warren is to many liberals' idea of a left movement that is within the political structure but outside the White House.

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If this movement gains attention, we'll probably hear plenty of comparisons to the Tea Party. The fact that there's a central political figure to this movement-an inspirational, if not an organizational leader-is just one of the things that distinguishes the two. I'm not sure that even the most hopeful liberals imagine they could mount the kind of full-scale takeover the Tea Party managed with the GOP.

But there are similarities too, especially in the way that many liberals see Barack Obama as being fundamentally weak and unwilling to fight, just as Tea Partiers are infuriated by what they see as the Republican leadership's knuckling under to Obama. And that, interestingly enough, is what provides an opening for Hillary Clinton to win the support of the Democratic Party's Warren wing.

Assuming Warren doesn't run, Clinton will have some work to do in order to win those activists and voters over. Clinton has always had centrist inclinations, particularly on foreign affairs (no one has forgotten her vote in favor of the Iraq War), and so she is viewed with suspicion by the left. But if she looks to her 2008 campaign, she might see exactly what she needs.

In 2007, Mark Schmitt, then the editor of this magazine, defined the Democratic presidential contest as the "theory of change" primary. As Clinton herself put it at the time, some people think you demand change (that was John Edwards), some think you hope for it (Obama), but she believed you work for it. Change "work" to "fight," and she could offer nearly the same message and warm the hearts of liberal activists who believe Obama has been too passive. And Republicans' undying hatred for Clinton-which will, I promise you, become dramatically more intense as the prospect of her becoming president of the United States becomes a proximate reality-will only serve to convince liberals that supporting her means getting into just the all-out war with the right they've been yearning for.

All talk of "Dems in disarray" aside, there are reasons why all Democrats can be happy about a resurgent left that is willing to challenge the Obama administration. In contrast to what the Tea Party does to the Republicans, a newly coherent and organized left is unlikely to impede any of the party's practical goals, nor is it likely to damage the party's image. The policy ideas favored on the left tend to be pretty popular, and liberal lawmakers aren't pushing for anything destructive like government shutdowns.

What they may do, however-and what the Tea Party did with such extraordinary effectiveness-is mobilize their party's base, to vote and contribute and organize. As a presidency weighed down by compromises and disappointments (for all its genuine achievements) winds down, there are few things the Democratic Party needs more than that kind of energy.