At stake for Dems in 2015? Only the future of the party

As the lights go down on 2014, it's looking like next year will feature a bruising fight for the future of the Democratic Party.

The tug of war on the right between the establishment's desire to govern and the tea party caucus' passion to take on President Barack Obama at every turn will certainly continue. But the bigger battle in 2015 will shift to the other side of the aisle as the ascendant progressive wing, led by charismatic Massachusetts Sen. Elizabeth Warren, will continue to clash with the administration and more moderate Democrats over Wall Street reform, federal spending, nominees and other issues.

The battle is already well underway as demonstrated by the liberal revolt that nearly toppled the year-end "Cromnibus" spending bill. The White House enraged liberal Democrats including Warren and House Minority Leader Nancy Pelosi by endorsing the deal even though it rolled back a piece of the Dodd-Frank Wall Street reform act governing derivatives.

Sen. Elizabeth Warren (D-Mass.) (5th L) speaks to members of the media as (L-R) Sen. Patty Murray (D-Wash.), Senate Majority Leader Sen. Harry Reid (D-Nev.), Sen. Jon Tester (D-Mont.), Sen. Amy Klobuchar (D-Minn.), and Sen. Charles Schumer (D-N.Y.) listen after a Democratic Senate leadership election at the U.S. Capitol Nov. 13, 2014.
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The White House decided that the funding levels in the spending bill and the certainty of its eliminating more near-term attacks on the president's health-care and immigration initiatives outweighed the Wall Street giveaway.

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The administration is also refusing to back down on the nomination of Lazard banker Antonio Weiss for the No. 3 slot at Treasury, sparking even more fury from the left.

Warren took to the Senate floor Friday night and delivered a stemwinder ripping the White House for catering to the desires of Citigroup lobbyists and taking renewed aim at the Weiss nomination.

"Enough is enough with Wall Street insiders getting key position after key position and the kind of cronyism that we have seen in the executive branch," Warren thundered in a speech some on the left likened to William Jennings Bryan's famous "Cross of Gold" address in 1896. The speech now has nearly 300,000 YouTube views.

As Democrats return to Congress as the minority party in the House and Senate next year these fights are likely to continue.

The White House will need to court Republicans to get Weiss and any other centrist nominees confirmed. The administration may also want to make a push to get another legacy accomplishment in the form of significant corporate tax reform. Liberal Democrats are likely to revolt over anything that lowers the top corporate rate without raising significant new revenues through closing existing corporate deductions.

Obama, meanwhile, can now cut deals with Republicans while completely freezing out congressional Democrats, if he chooses to go that route.

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That would be a highly risky strategy as he will need Democrats in the Senate to back him up and sustain his veto should he need to use it to block changes to Obamacare or other major accomplishments.

All of this will also coincide with the start of the 2016 presidential nominating contest. Right now, Hillary Clinton still enjoys unquestioned nominee-in-waiting status for the Democratic nomination, with massive polling leads in early primary and caucus states.

But as we saw in 2008, things can change quickly. Clinton has gone from certain coronation to primary loser before. Her position is even stronger this time. And there is no Barack Obama on the horizon. Unless there is.

Warren says she is not running. And she probably isn't. But should she decide to run she would electrify progressives who are increasingly disillusioned by both Obama and Clinton. Warren could channel both anger at Wall Street and anger at Clinton's hawkish foreign policy. Support for the Iraq War helped topple Clinton in 2008 and the issue has not lost its potency.

Even if Warren doesn't run, there will certainly be some kind of challenge to Clinton from the left. Democrats typically do not engage in primary coronations. And whoever emerges will push Clinton left and possibly complicate her general election prospects, especially if she squares off against a formidable Republican such as former Florida Gov. Jeb Bush who could take both his home state and threaten the Blue Wall of Democratic states in the Northeast.

Bush is preparing to release hundreds of thousands of emails from his days as governor as well as publish an e-book, suggesting he is leaning toward a run.

It's far from a certainty that battles on the left will overtake Republican infighting as the political story of 2015. But early signals certainly point in that direction as the party begins to define a post-Obama direction heading into a 2016 campaign that could conceivably wind up with total Republican control of Washington.

—By Ben White. White is Politico's chief economic correspondent and a CNBC contributor. He also authors the daily tip sheet Politico Morning Money [politico.com/morningmoney]. Follow him on Twitter @morningmoneyben.