On Monday, Sen. Kamala Harris kicked off her campaign for president by attempting to establish her Democratic credentials, which in 2020 means embracing Medicare for All, a policy proposal that fueled Bernie Sanders’ campaign in 2016 but that the eventual nominee, Hillary Clinton, dismissed as unworkable.

"Let's eliminate all of that,” Harris said of private insurance plans. “Let's move on."

Welcome to the Democratic primary, where the price of entry is the embrace of several policy ideas once-considered leftist but now solidly mainstream within the Democratic Party — Medicare for All, a Green New Deal, regulating Wall Street, and the opportunity to get a free or debt-free college education. Even centrist candidates like Harris, who built her resume as a tough-on-crime career prosecutor, are on board.

"Last cycle, progressives fought hard to make issues like a $15 minimum wage and Medicare for All part of the national debate, but now they are increasingly the mainstream Democratic position,” Joe Dinkin, campaigns director of the Working Families Party, which helps elect progressive candidates nationwide, told VICE News.

Here are the progressive ideas that Democrats will have to get behind if they want the 2020 nomination:

Medicare for All

Plenty of viable 2020 candidates — including Harris, Sen. Elizabeth Warren, Sen. Cory Booker, and Sen. Kirsten Gillibrand — have already endorsed or co-sponsored Sanders’ latest Medicare for All draft bill, a remarkable turn of events considering virtually no establishment Democrats supported the measure in 2016. Sen. Sherrod Brown of Ohio, who is considering a presidential run, is a notable exception. He has long expressed support for single-payer healthcare but didn’t sign on to Sanders’ latest bill and has recently become critical of Medicare for All because he believes an incremental strategy is more effective.

At this point, Democrats like Brown and former Vice President Joe Biden stand out more because they don’t explicitly come down in favor of Medicare for All. Just how Medicare for All would be funded and implemented remains hotly debated. Though Sanders and other champions of the idea see no need for private buy-in plans, more-moderate Democrats worry the idea is too transformative. Most supporters agree that private doctors and hospitals would still exist.

A Green New Deal

A Green New Deal aims to divest the U.S. from fossil fuels by investing in green infrastructure and jobs before the effects of climate change become irreversible in the next 12 years, as climate scientists warn. Meaningful action against climate change has received sweeping support from prospective Democratic nominees.

The widespread endorsement of the Green New Deal has a caveat: The policy proposal is more of an opaque idea than an explicit course of action, so nobody is quite sure what exactly a Green New Deal would enact or just how radically it would change the American energy industry. In a general sense, a Green New Deal would transform the American economy by replacing carbon power sources with clean-energy infrastructure and jobs. As Rep. Alexandria Ocasio-Cortez put it in her first pitch, the Green New Deal would provide workers “the opportunity, training and education to be a full and equal participant in the transition, including through a job guarantee program to assure a living-wage job to every person who wants one.”

Going after Wall Street and money in politics

As populist ideas like Medicare for All take center stage in the 2020 primaries, Democrats will have to turn against an enormously powerful foe — Wall Street — to both finance their ambitious proposals and prove they’re standing up for the working class.

"It can't be Warren and it can't be Sanders," the CEO of a "giant bank" anonymously told Politico this week.

Still, the Democratic playing field has shown a stark evolution from 2016, when Hillary Clinton repeatedly came under fire for accepting millions upon millions in super PAC money as well as huge checks to give private speeches to big banks.

This time around, Democrats are eager to distance themselves from Wall Street. Almost every candidate vying for the 2020 ticket has sworn off corporate PAC money and prioritized individual donations to avoid influence from special interests.

Most 2020 candidates, however, aren’t historically reliable enemies of big banks, and some — like Sen. Kirsten Gillibrand of New York and former Vice President Joe Biden — have already weathered backlash for their cozy relationships with Wall Street and billionaires.

Free or debt-free college

The issue of affordable higher education is a bit thornier for Democrats, but every candidate has backed some form of free college. As usual, Sanders and Warren emerge as the hard-line progressives on the issue. The duo has previously collaborated to make public colleges tuition-free, and both have been prominent advocates of student-loan debt relief and forgiveness. Sanders campaigned on the issue during the 2016 Democratic primary.

When it comes to Harris, Castro, Gillibrand, and beyond, the positions get a bit murkier. Harris, for example, said she supported “debt-free college” and the elimination of for-profit colleges, though she hasn’t spoken about debt relief for people paying off student loans. Castro initially said he supported “accessible and affordable” college education programs, though he later said he wanted “tuition-free” college, after he received backlash from progressives.

Criticizing Israel

Democrats usually avoid criticizing Israel, although politicians are facing mounting pressure from their progressive base to speak out against the country’s continued occupation of the West Bank, forcible eviction of Palestinian residents, and use of violence against Palestinians. Amnesty International said Israeli forces “unlawfully killed Palestinian civilians, including children, and unlawfully detained within Israel thousands of Palestinians” in 2017 and 2018. It’s stirred up backlash for even the progressive Left’s most darling candidates, like Bernie Sanders.

Prominent leftist political groups such as the Democratic Socialists of America (DSA), which endorsed Sanders in 2016, have expressed support of the Boycott Divestment Sanctions (BDS) movement against Israel’s occupation of Palestinian territories. Sanders took heat Monday for saying he did not support the BDS movement.

BDS remains a mostly taboo subject for prominent Democrats, many of whom just voted in favor of legislation that would seek to curb the movement and its support of Palestine. Just two sitting members of Congress — freshman Reps. Ilhan Omar of Minnesota and Rashida Tlaib of Michigan — openly support BDS, and centrist Democrats have mounted efforts to publicly ridicule them.