Asma Khalid

About three weeks ago, Vermont Sen. Bernie Sanders had a heart attack that threw his campaign into question. But now, it's more apparent than perhaps at any point in this presidential race that the 78-year-old white-haired politician and his revolution will remain a powerful force in the Democratic primary.

Former Vice President Joe Biden unveiled an ethics plan on Monday that directly targets President Trump, accusing him of creating the "most corrupt administration in modern history." It's a sign the Democratic presidential candidate is ramping up his defense ahead of the fourth Democratic debate in Ohio on Tuesday.

Jeromy Brown, a 46-year-old teacher in Iowa, considers President Trump a white supremacist.

"If the shoe fits, then say it, and the shoe fits him," Brown said, while waiting in a photo line at an Elizabeth Warren rally in August. "Why should he be excused from that label?"

Massachusetts Sen. Elizabeth Warren introduced a sweeping gun control plan Saturday with the goal of reducing gun deaths by 80% through executive action and legislation.

"You've got to start with a goal. I haven't heard anybody else talk about a goal," Warren said in an interview with The NPR Politics Podcast. "What I've heard them talk about is here's one thing we'll do, and one thing we'll do, and one thing we'll do, and then we'll quit."

Before the first presidential debate last month, former Vice President Joe Biden's campaign signaled that he expected to be attacked by the candidates trailing him in the polls but that Biden would essentially ignore all incoming fire.

It was a classic front-runner approach. And it was punctured, hard and fast, by California Sen. Kamala Harris' attack on Biden's past opposition to federal busing policies.

Justin Krebs, a campaign director with MoveOn, isn't interested in hearing pundits debate which 2020 Democratic candidate is the most "electable."

"Because exactly four years ago right now there was a messy, crowded primary, with too many candidates, people who were totally unelectable, and Donald Trump was one of them and ended up winning," he pointed out.

And in the same vein, many Democrats thought Barack Obama was unelectable until he started winning primaries in 2008.

Progressive activists feel like this is their moment.

Their values are no longer seen as fringe ideas in the Democratic Party. Multiple presidential candidates are talking about "Medicare-for-all," reparations for slavery and bold action on climate change. And their ideas are driving the action on debate stages.

Now, as they gather in Philadelphia for the largest progressive convention of the year, Netroots Nation, they feel empowered as if this is their time to take over the party, push traditional Democrats aside and hold candidates accountable.

New Jersey Sen. Cory Booker, one of half a dozen Democratic senators running for the White House, is reintroducing a bill on Thursday that would fundamentally end the federal government's prohibition on marijuana.

When bipartisan immigration discussions pop up, Democrats often insist it's hard to find a solution because of the GOP's immigration evolution. The days of Ronald Reagan endorsing an amnesty program and denouncing walls are long gone, replaced by President Trump's talk of "rapists" and quest for a wall.

Given the historically large number of Democrats expected to run for president in 2020, the Democratic National Committee is preparing to host the first two primary debates, with each debate split into two consecutive nights to accommodate up to a maximum of 20 candidates.

The DNC announced details Thursday for the first two primary debates of the season.

The first debate, scheduled for this June, will be broadcast on NBC, MSNBC and Telemundo. The second debate, slated for July, will be broadcast on CNN.

In the spring of 2015, before Bernie Sanders had a campaign office in New Hampshire, Elizabeth Ropp, an acupuncturist, was making homemade signs for the Vermont senator.

"Bernie inspired me because as somebody who's lived without health insurance for most of my adult life, I want there to be a single-payer health care system," she said.

She was disappointed Sanders wasn't the nominee and is convinced that if he had been, Donald Trump would not be president.

"I want to see Bernie run again in 2020," said Ropp. "We need Bernie to run even if the field is crowded."

Updated at 9:24 a.m. ET

When Elizabeth Warren announced her exploratory committee for president at the end of last month, the Massachusetts senator didn't only talk about a crumbling middle class - her signature policy issue - but she acknowledged the impact of race and racism on the economy, saying that "families of color" face a rockier path "made even harder by the impact of generations of discrimination."

Angie Beem used to be a woman who, at most, would read the voter pamphlet before Election Day, cast a vote, and consider her duty done. She didn't pay attention to politics much because she didn't think it affected her life.

But that all changed ahead of the 2016 presidential election when she noticed Facebook posts that deeply troubled her.

"My family were starting to be racist and saying horrible things," said Beem. "I didn't recognize them."

Marilynn Leggio, 71, brought her teenage granddaughter with her to an Elizabeth Warren rally in Council Bluffs, Iowa, last Friday evening.

Leggio says she has "no doubt" the Massachusetts senator would do a "good job" as president, but given Hillary Clinton's loss in 2016, she's not sure whether the country will take a chance on another woman in 2020.

"I think there's a lot of men out there that would never vote for a woman," said Leggio. "I hate to say that, but I think that. Especially a woman that's strong, very opinionated. I think a lot of men think she's pushy."

Supreme Court Justice Ruth Bader Ginsburg was discharged from the hospital on Christmas Day following surgery for early stage lung cancer, according to a Supreme Court spokesperson.

Ginsburg is now "recuperating at home," after doctors at Memorial Sloan Kettering hospital in New York performed surgery on Ginsburg to remove cancerous growths found on her left lung.