The news is breaking this morning that Harry Reid will not run for reelection, which will set in motion a scramble for power at the top of the Democratic Senate leadership. This, in turn, will intensify the debate between the rising “Elizabeth Warren wing of the Democratic Party” and its (somewhat) less populist wing over what sort of economic agenda the Democratic Party should represent.

This debate is already underway: Two liberal groups are now floating the idea of a Warren run for the post of Democratic Senate leader.

Judging by the Twitters, most political observers have already decided that the two major contenders for the post will be Chuck Schumer and Dick Durbin, with Schumer seen as the heavy favorite. That may be true, but that doesn’t mean the liberal wing of the party will quietly acquiesce without trying to put its stamp on the outcome.

“If Elizabeth Warren doesn’t run for president, she should definitely run for leader of the Senate,” Neil Sroka, a spokesman for Howard Dean’s Democracy for America, tells me. “The election for Senate leader is not going to be a slam dunk for any early front-runner, especially someone like Senator Schumer. He’s closer to Wall Street while the Wall Street wing of the party is dying and the Elizabeth Warren wing is rising. It only makes sense that the next leader of the U.S. Senate is either from that wing or deeply understands how to work with that wing.”

“There will likely not be a coronation to replace Harry Reid, and Elizabeth Warren is right up there with others as someone who would be taken very seriously,” the Progressive Change Campaign Committee tells me in a statement. “Warren’s lifetime of fighting for the little guy against Wall Street power — including her upset victory on the Consumer Financial Protection Bureau — shows she can think big, wage tough fights against powerful interests, and win key votes in the Senate. She’s the definition of a leader, and that’s why her colleagues and millions of Americans respect her and are inspired by her rise.”

The point here is not that Warren will run, or that the left will necessarily be able to install their chosen candidate at the top of the Dem Senate leadership. Rather, it’s that the left will use this occasion to try to pull the debate at the center of the battle to succeed Reid to the left on a range of issues.

For instance, liberal groups note that late last night, 42 Democratic Senators voted for an amendment to expand Social Security, a priority of liberal groups that was once considered laughably far outside the mainstream. The influence of Warren, who made a big splash by endorsing expanding Social Security, probably played a key role in corralling that vote. While Schumer voted for the amendment, too, the question will be which Senators are truly willing to fight for this priority.

Then there’s trade. The big Trans-Pacific Partnership deal will likely be announced soon. Schumer has been raising alarms about the need for safeguards against currency manipulation as part of it, so in some ways he’s been protecting his left flank on trade. But there is still plenty of room for deep intra-Dem disagreements on any final trade deal. On financial reform, Warren famously led a Dem revolt against a provision in the recent budget deal that weakened protections against risky Wall Street trading, which foreshadows possible disagreements ahead among Democrats over how aggressively to maintain Wall Street accountability.

To be sure, there is probably more consensus among Democrats on economic matters than there has been in many years. But real differences remain, and if liberal groups get their way, they will be litigated in the context of any battle to succeed Reid. Even if Warren doesn’t run, the left will try to exert influence over any others who might emerge — Durbin or possibly Patty Murray — in hopes of also pulling Schumer in their direction.

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* SENATE PASSES BUDGET THAT SHREDS SAFETY NET: It passed by 52-48, and Reuters’ headline captures it nicely: “Senate passes Republican budget with deep safety net cuts.” The Reuters story nicely captures the chicanery here:

The Senate passed a Republican-authored budget plan early on Friday that seeks $5.1 trillion in domestic spending cuts over 10 years while boosting military funding….The Senate budget seeks to eliminate U.S. deficits by 2025 without raising taxes through deep cuts to social safety net programs, investments in transportation and education and other domestic programs.

Sounds legit! And all this may understate matters. Reminder: According to the Center of Budget and Policy Priorities, to get to balance within 10 years with zero new revenues, more than two thirds of the budget’s cuts will have to fall on programs that help those with lower incomes.

* HOW GOP PRESIDENTIAL CANDIDATES VOTED ON THE BUDGET: Also noteworthy: Senators Ted Cruz and Rand Paul voted against the Senate budget, but Marco Rubio and Lindsey Graham voted for it. As noted here yesterday, the GOP budget, with its deep cuts to programs that help lower income Americans confirms that the Republican Party’s inequality agenda is still heavily premised on the idea that there is too much downward redistribution of wealth.

Rubio and Graham are all in; Cruz and Paul presumably opposed it because it didn’t cut enough. Hopefully we’ll soon hear from Jeb Bush and Scott Walker on it.

* JEB BUSH’S STEALTH EFFORTS TO WOO RELIGIOUS CONSERVATIVES: Worth reading: National Journal has a very deep dive into Jeb Bush’s Catholicism and his quiet efforts to win over religious conservatives and evangelicals. Can Bush appeal to the “more pragmatic evangelical and Catholic leaders” who might not be reflexively drawn to the “outspoken Christian warriors” in the GOP primary (Ted Cruz) who are flaunting their combative stance on gay marriage and other issues?

I’ll be interested to see whether Bush makes immigration reform, which many evangelicals support, a key to his pitch to these voters.

* LIBERALS AND CONSERVATIVES INHABIT ALTERNATE REALITIES: Paul Krugman claims there is just nothing on the left that compares to conservatives’ worship of Ronald Reagan and their denial of reality about the economic recovery under Obama and the Affordable Care Act, and gets at the reason why:

The economy added 23 million jobs under Clinton, compared with 16 million under Reagan, but there’s nothing on the left comparable to the cult of the Blessed Ronald. That’s because liberals don’t need to claim that their policies will produce spectacular growth. All they need to claim is feasibility: that we can do things like, say, guaranteeing health insurance to everyone without killing the economy. Conservatives, on the other hand, want to block such things and, instead, to cut taxes on the rich and slash aid to the less fortunate. So they must claim both that liberal policies are job killers and that being nice to the rich is a magic elixir.

* AND TEAM HILLARY DELIBERATES OVER CAMPAIGN LAUNCH: Glenn Thrush reports on what is likely to come right after Hillary Clinton’s much-anticipated presidential announcement:

Clinton, according to several people familiar with the still-in-flux planning process, will embark on a short tour that will almost certainly include Iowa – and perhaps other states – to interact with voters in a series of events, most of them in low-key settings…her team is keen to speed her transition from aloof global personality to the kind of down-to-earth campaigner who emerged during the latter half of the 2008 primary season.

Folks have mostly forgotten, because she lost the 2008 primary to some guy named Barack Obama, but Clinton actually emerged as a surprisingly good campaigner in the home stretch of that race.