With 162 days until the Iowa caucuses and and a barely winnowed Democratic field still vying for the nomination, the 2020 election will be here before you know it. Every Sunday, I outline the 5 BIG storylines you need to know to understand the upcoming week on the campaign trail. And they're ranked -- so the No. 1 story is the most important.

(CNN) 5. Do Democrats needs more debates?: With the deadline to qualify for the third Democratic National Commitee-sanctioned debate arriving this week -- much more on that below -- there's another fight breaking out on the debate front: Should the candidates be doing more of them?

The decision was immediately criticized by, among others, former Texas Rep. Beto O'Rourke. "This decision is as baffling as it is alarming," O'Rourke tweeted . "Our planet is burning -- the least we can do as a party is debate what to do about it."

As the DNC seeks to both control and winnow the field over the coming months -- more than half of the candidates running have not qualified for the next debate in September -- criticism of its methods will grow. Many candidates running on the fringes of relevance badly need the debates to remain viable in the race and, their campaigns hope, create a viral moment that can change everything.

The DNC must balance its desire to produce the best possible nominee against President Donald Trump with its own history; in 2016, emails published by WikiLeaks made clear that certain elements within the DNC -- all of whom were removed before the start of the 2020 race -- had their thumb on the scale for Hillary Clinton over Bernie Sanders.

4. "Medicare for All" fight rages: The largest -- and most important -- emerging fight among 2020 Democrats is over their support (or lack thereof) for "Medicare for All," a program, pushed by Vermont Sen. Bernie Sanders, that would entirely eliminate the private health insurance industry if implemented.

Sanders found himself at the center of the firestorm this past week, beating back allegations from his more centrist opponents that he was changing his plan to appease some union supporters. His campaign vehemently denied that accusation. (You can read all the back-and-forth here.

California Sen. Kamala Harris continued to retreat from her past full-throated support for Sanders' "Medicare for All" proposal; "I've not been comfortable with Bernie's plan," she said at a fundraiser last weekend

The wishy-washiness could well be the result of polling that suggests that even hardcore Democrats aren't totally sold on the idea of getting rid of all private health insurance, preferring to keep the option open even in a system which creates a more robust public marketplace. That position is close to where former Vice President Joe Biden stands on the issue -- proposing a single-payer plan as one of the options within the broader framework of the Affordable Care Act.

3. Does Nevada matter?: Quick -- name the key early voting states in the 2020 nominating process. Most of you likely named Iowa or New Hampshire. Maybe a few threw out South Carolina. But if this group is anything like the political class more generally, Nevada barely got a mention. Which is weird because the state is expected to hold the third official vote of the race on February 22 -- 11 days after the New Hampshire primary and a week before the South Carolina primary.

The question no one knows the answer to is whether winning Nevada will really matter. In 2016, Clinton edged Sanders in the sate's caucuses but that victory represented barely a ripple in the broader fight for the nomination. Clinton also won the Nevada caucuses in 2008, edging Barack Obama in the state. It did little to stop Obama's march to the nomination.

Starting Wednesday, a handful of 2020ers will swing through the state to address the Nevada AFL-CIO. Among those expected to be there: New Jersey Sen. Cory Booker, Minnesota Sen. Amy Klobuchar, Harris, former HUD secretary Julián Castro and New York City Mayor Bill de Blasio. A surrogate for Biden is expected to speak the the labor gathering on Thursday.

To date, Castro has visited the state most, according to a tracker maintained by the Nevada Independent . That makes sense, as Castro is the lone Hispanic candidate in the field and Nevada has the largest Hispanic population of any of the four early voting states. Harris and self-help guru Marianne Wiliamson are close behind in Nevada visits, with six each.

The question no one knows the answer to is whether winning in Nevada truly matters to the next Democratic nominee.

2. Trump's got a primary now: On Sunday, former Illinois Rep. Joe Walsh made it official: He's challenging President Donald Trump in next year's primary. "I'm going to run for president," On Sunday, former Illinois Rep. Joe Walsh made it official: He's challenging President Donald Trump in next year's primary. "I'm going to run for president," Walsh said on ABC's "This Week." "I'm going to do whatever I can. I don't want him (Trump) to win. The country cannot afford to have him win. If I'm not successful, I'm not voting for him."

How worried should Trump be? Not worried. For all of his boastings and untruths, one thing Trump is right about is how incredibly popular he is among the Republican base. In Gallup's most recent job approval tracking poll, Trump is at 41% overall but at 88% among Republicans. And you don't beat someone who almost 9 in 10 people like.

Walsh, of course, knows that. His candidacy is less about winning and more about making a statement. What is the statement? Not all of the Republican Party has capitulated to Trump. Opposition remains.

The problem for Republicans trying to make the case that the GOP is not just the party of Trump is that Walsh is a very imperfect messenger. A one-term member of Congress from suburban Chicago, Walsh made a name for himself in conservative circles by touting the idea that Obama was not born in the United States. Former Massachusetts Gov. Bill Weld announced in April that he would also challenge Trump.

1. It's (almost) debate deadline day: This Wednesday -- the 28th -- is the final day that any 2020 Democratic candidate can qualify for the third debate, which is set for September 12 (and 13th if necessary) in Houston.

At the moment, 10 are in for sure: Biden, Booker, South Bend, Indiana, Mayor Pete Buttigieg, Castro, Harris, Klobuchar, O'Rourke, Sanders, Massachusetts Sen. Elizabeth Warren and businessman Andrew Yang.

There are three others with some hope of making the cut between now and Wednesday night: businessman Tom Steyer, Hawaii Rep. Tulsi Gabbard and New York Sen. Kirsten Gillibrand. Of the trio, Steyer is the closest, having already met the 130,000 individual donor threshold and needing only one more poll -- in an early state or nationally -- that shows him receiving 2% support or more. (Candidates need four total polls at 2% or higher to qualify.) Gabbard has also met the fundraising criteria but needs two more polls. Gillibrand has one poll with her at 2% but remains short of the fundraising floor.

Assuming Gillibrand and Gabbard come up short -- which now looks like the most likely outcome -- you will have two sitting senators (Gillibrand and Colorado's Michael Bennet) two House members (Gabbard and Ohio Rep. Tim Ryan), a governor (Montana's Steve Bullock) and the mayor of the country's biggest city (New York's de Blasio) all left out of the debate next month.

For all of those candidates, this week will be a moment of reckoning. Going to your donors or even your staff and making the case to stay in the race gets infinitely more difficult when you can't even meet the debate qualifications.

Two candidates -- Washington Gov. Jay Inslee and Massachusetts Rep. Seth Moulton -- dropped from the race last week alone. A few others may well join them on the sidelines sometime very soon.