• And she’s virtually assured to lack the kind of majorities she’d need to pass them, according to Democratic staffers and former White House officials from both parties.

Details: Even under the most optimistic scenario for Democrats — keeping the House and narrowly winning back the Senate from the Republicans — Warren wouldn’t have solid Democratic support for her biggest ideas, including the wealth tax, Medicare for All and the Green New Deal.

• Her college debt plan would likely get a major rewrite from fellow Democrats, in a best case scenario.
• They’re unlikely to go along with a full repeal of the GOP tax cut to set the stage for her corporate profits tax, according to Senate Democratic aides. And she’d have a solid wall of Republican opposition in the Senate, regardless of who wins the majority.
• Warren’s answer to that problem is to eliminate the filibuster so Democrats can pass legislation with a simple majority — but she’d have a hard time doing that since some Democrats, like Kyrsten Sinema, say they’d never support it.

What they’re saying: “I don't think it's inappropriate for a candidate to campaign on her aspirations for the country, and to try to build support for a bigger vision than what is currently on offer,” said Cecilia Muñoz, who headed the White House Domestic Policy Council under Barack Obama and isn’t working for any of the presidential campaigns.

• “At the same time, I also think it's important to level with the country, because a big bold vision ultimately can take years to accomplish, and will require more than one election and much more than one leader.”
• Paul Winfree, who served as deputy director of the Domestic Policy Council under President Trump, said Warren would need Congress to pass “virtually everything of significance” on health care, banking, taxes, student loans and other issues.

The other side: If Warren wins the White House, she could do some significant things through executive action — including tougher antitrust enforcement to try to break up the Big Tech companies, as Axios’ Margaret Harding McGill points out.

• Warren could appoint an aggressive Financial Stability Oversight Council to provide much tougher oversight of America’s biggest banks, Axios’ Felix Salmon notes, even if it couldn’t go quite as far as separating commercial banks from investment banks entirely. (Her proposed 21st Century Glass-Steagall Act would still require legislation.)
• On insulin, EpiPens, and the anti-inflammatory drug Humira, Warren says she’d be able to reduce the price of some costly drugs and delivery devices through executive actions. That could mean using existing legal authority to bypass or re-license their patents; and pursuing antitrust action against Humira manufacturer AbbVie.
• She couldn’t ban all fracking without approval from Congress, but she could ban it on federal lands, per Axios’ Amy Harder — and that could still have a significant impact, even though most oil and gas is produced on private and state lands. She could also reinstate environmental regulations Trump has repealed and make them even more aggressive.
• Warren could effectively decriminalize border crossings, not by changing the law but through instructions from the Justice Department telling federal prosecutors not to prosecute those crimes, Axios’ Stef Kight reports.

The Warren campaign insists she could pass one of her most popular ideas — the wealth tax — through a budget reconciliation process that requires a simple majority vote in the Senate, and that she could use executive action to implement significant changes on health care, gun control and the environment.

• "Elizabeth has a proven record of making our government work for every person, not just the wealthy and well-connected. She will use every tool available to do the same as president," said campaign spokesperson Saloni Sharma.
• Other variables may affect what Warren could or couldn’t do if she wins — like the state of the economy by 2021, and any unforeseen crises.

The bottom line: Warren has built a campaign on her ability to lead through bold ideas, so it’s a good idea for supporters and critics alike to be clear-eyed about what she can actually get done.

Go deeper:

• Reality check on Warren's biggest ideas
• Elizabeth Warren on the issues, in under 500 words
• Elizabeth Warren takes on private equity
• Elizabeth Warren's dream health care world

1) Wealth tax: It’s a popular proposal, with solid support even among Republican voters, and it's one idea Warren could advance through budget reconciliation, which requires only 51 votes in the Senate.

But Warren’s idea of a 2% annual tax on household net worth of $50 million and over — with an additional 4% annual tax on amounts above $1 billion — would have a hard time passing in this form even among Democrats, largely because of the practical problems in implementing it.

• A Senate Democratic aide who works on tax issues said the IRS would have a tough time determining the value of private wealth for everyone who would be affected — noting that the Warren campaign acknowledged the IRS would have to "develop new valuation rules as needed" for certain assets.
• The Warren campaign, however, insists the tax would be easy to administer since it would be based on current IRS rules.

2) Medicare for All: The big sign this one is unlikely to materialize beyond the campaign trail: Democrats couldn’t even pass a public option — now considered the moderate alternative to Medicare for All — as part of the Affordable Care Act in 2009, when they had 60 votes in the Senate.

• There’s no scenario in which they’d have anything close to that size majority after the 2020 elections, even if they did manage to win control, at least under the current Senate map.
• Plus, Medicare for All’s support among all Americans tanked in the latest Quinnipiac University poll (although Democrats still like it).

3) College debt (eliminate $640 billion in student debt, establish free public college): Democrats broadly agree on the goal of making college more affordable, but they’re likely to debate the cost and whether any proposal should be targeted toward low-income people, according to a Senate Democratic aide who works on education issues.

4) Breaking up Big Tech: Warren intends to appoint officials at the nation’s antitrust agencies — the Federal Trade Commission and the antitrust division of the Justice Department — who are “committed to reversing illegal and anti-competitive tech mergers,” Axios’ Margaret Harding McGill reports.

• But while aggressive antitrust enforcement is almost a given under Warren, that’s only the beginning of the story when it comes to breaking up a company.
• “In the end, it’s the courts that decide if there’s an antitrust violation and what the appropriate remedy is,” said Gene Kimmelman, a former DOJ antitrust official who’s now a senior adviser at Public Knowledge, a nonprofit that focuses on tech issues. “It will probably be an uphill battle to break everybody up.”

5) Green New Deal: The sweeping plan — which includes federal guarantees for health care, housing and jobs on top of aggressive climate change and clean energy goals — would almost certainly fail in the next Congress, given how many moderate Democrats have been skeptical of it and the virtual certainty that Republicans would oppose it.

6) Corporate tax (7% tax on companies’ profits over $100 million): This one’s tougher to call given that Senate Democrats just aren’t talking about it, according to a Senate Democratic aide — but the silence certainly doesn’t suggest a burning desire for it.

• And the corporate tax rate itself, which was cut from 35% to 21% in the 2017 tax cut law, isn’t likely to be reversed completely — since even Democrats wouldn’t all agree to raise it back to 35%, the aide said.

7) Banks (21st Century Glass-Steagall Act to separate commercial banks from investment banks): Warren would need legislation to carry that out, Axios’ Felix Salmon reports — but she could appoint aggressive members of the Financial Stability Oversight Council, an entity created by the Dodd-Frank banking overhaul.

8) Private equity: Ideas like making buyout funds liable for leveraged financing — and banning them from paying themselves monitoring fees — aren’t about to get through Congress, at least under the current makeup, as Axios’ Dan Primack has written. (His one caveat: there could be more tailwinds for her ideas if she wins.)

9) Decriminalize immigration violations: This idea — which isn’t popular even among Democrats — could be within Warren’s reach, as a Warren Justice Department could just issue instructions not to prosecute border crossings, per Axios’ Stef Kight.

10) Fracking ban: Warren could ban the controversial oil and gas extraction method on federal lands, but a ban on private and state lands would need approval from Congress, Axios’ Amy Harder reports.

Go deeper:

• The steep odds against Warren's big ideas
• Elizabeth Warren on the issues, in under 500 words
• Elizabeth Warren takes on private equity
• Elizabeth Warren's dream health care world

Warren collapsed in the latest national Quinnipiac University poll just as she's been diving into the details of how she'd pass Medicare for All — and fending off a barrage of attacks from her more moderate rivals.

• She's not the only Democrat who's run into trouble. Kamala Harris realized she could be checkmating herself by dismissing private health insurance — which is why she changed her Medicare for All plan to allow private insurers to offer Medicare plans.
• And in an interview for "Axios on HBO," she told Axios' Margaret Talev she knew there could be a political price to pay for changing her plan — but says she told her team that "we need to do a better plan. This is not good enough."

There's a reason Medicare for All has dominated every health care discussion at every debate, as Axios' David Nather points out: it's a real problem for the liberal candidates. Not just because of the cost, but because not all Americans actually want to dump private health insurance.

• Even Warren's phase-in plan isn't quieting the critics. As Axios' Caitlin Owens has pointed out, progressives are criticizing her for not being a Medicare for All purist — and experts are skeptical that she could really pass two major reforms within a few years of each other.
• Now Biden and Buttigieg are firing away at her over whether Americans would really have a choice if they wanted to keep their private health insurance — while Bernie Sanders subtly competes with her by staying a purist.

Sanders, who introduced the Medicare for All Act, has always been candid about his intent to wipe out private health insurance as part of his plan.

• He hasn't faced as many attacks or struggled with the issue as much as Warren.
• As a result, he isn't plummeting in the polls. But he hasn't enjoyed Warren's earlier gains, either; Sanders' support has held in the high teens throughout 2019, according to RealClearPolitics, which tracks polling averages.

By the numbers: Medicare for All is a favorite among Democrats who are fed up with private insurance — but it's not a winner with swing voters.

• Per the Kaiser Family Foundation's Drew Altman, recent polling by Kaiser and the Cook Political Report found that 62% of Democrats in four battleground states — Pennsylvania, Minnesota, Michigan, and Wisconsin — said a Medicare for All plan that eliminates private insurance is a good idea.
• But 62% of swing voters in those states said it’s a bad idea.

Between the lines: Caitlin notes that since Warren has been on defense on this, the potential appeal of Medicare for All hasn't been discussed as much as its cost and the merits of taking away a private insurance option.

• So we spend more time debating that rather than what life would be like for Americans if they didn't have any health care costs.
• In other words, Warren has had to spend a lot of time defending the downsides of Medicare for All (its cost) instead of its upsides (free health care for everyone).

Our thought bubble: 2020 Dems could also be miscalculating the broad appeal of other liberal stands, including free college and decriminalizing border crossings.