(CNN) With 169 days until the Iowa caucuses 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.

5. Bullock bucks overtures (but for how long)?: Montana Gov. Steve Bullock isn't planning to switch from the presidential race to challenge Republican Sen. Steve Daines anytime soon.

"I will do everything I can to get who we nominate from Montana elected," Bullock said on "Fox News Sunday." "It won't be me."

Bullock will be in Iowa on Wednesday to speak at the state AFL-CIO convention in Des Moines, yet more evidence of his hopes that an Iowa-centric campaign gives him the best chance to break through in the (still) massive 2020 field.

Which isn't a bad theory of the case! But Bullock has yet to gain any sort of traction in the Hawkeye State or anywhere else -- and he is nearly certain to miss the next Democratic debate. (Much more on that below!)

4. Trump's back!!: After spending 10 days at his hotel and golf club in New Jersey, President Donald Trump is back and working in Washington this week. HIs schedule is relatively light. He has nothing on it Monday. Tuesday, Trump has lunch with Vice President Mike Pence and sits down with Romanian Prime Minister Klaus Iohannis. He'll be in Louisville on Wednesday for a veterans event. On Friday he meets with Secretary of State Mike Pompeo.

As always with Trump, of course, his Twitter feed may be where the action is. And early returns on his mindset suggest we should all buckle up. The President sent a slew of retweets on everything from the possibility he might run for more than two terms to assertions that his crowd in New Hampshire last week was record-breaking.

Trump also took time to slam his favorite target: The media. Tweeteth Trump

"The Failing New York Times, in one of the most devastating portrayals of bad journalism in history, got caught by a leaker that they are shifting from their Phony Russian Collusion Narrative (the Mueller Report & his testimony were a total disaster), to a Racism Witch Hunt. 'Journalism' has reached a new low in the history of our Country. It is nothing more than an evil propaganda machine for the Democrat Party. The reporting is so false, biased and evil that it has now become a very sick joke...But the public is aware! #CROOKEDJOURNALISM"

What's Trump talking about, specifically? Your guess is as good as mine. But he's saying it loudly.

3. Biden's GOP-friendly message: Over the weekend, at a fundraiser in Cape Cod, former Vice President Joe Biden said this:

"There's an awful lot of really good Republicans out there. ... I get in trouble for saying that with Democrats, but the truth of the matter is, every time we ever got in trouble with our administration, remember who got sent up to Capitol Hill to fix it? Me. Because they know I respect the other team. I do. They're decent people. They ran because they care about things, but they're intimidated right now."

Which is a line -- or a variation of a line of thinking -- he's been using since he entered the 2020 race several months ago. It's also a reminder of just how different a campaign Biden is running than all the other top-tier Democratic candidates.

Biden is saying that Republicans are caught up in a Trump fever right now, but when the President loses, they will return back to their pragmatic selves almost immediately. All of his rivals for the nomination view Trump as a symptom of broader Republican issues that have been percolating for some time, not the cause. And they insist that whether or not Trump wins again, the GOP isn't ever going to go back to those halcyon days Biden imagines.

The question is how long Biden can keep the Republicans-aren't-so-bad message going in the face of a Democratic base that fundamentally disagrees with him about the nature of the opposition.

2. Who will make the September debate?: There are 10 days left for 2020 Democrats to qualify for the third There are 10 days left for 2020 Democrats to qualify for the third debate in Houston in September. To make it, candidates need a) 130,000 individual donors from 400 unique people in 20 states and b) 2% in at least four Democratic National Committee-approved polls.

At the moment, these nine candidates are in for sure: Biden, New Jersey Sen. Cory Booker, South Bend, Indiana, Mayor Pete Buttigieg, California Sen. Kamala Harris, Minnesota Sen. Amy Klobuchar, former Rep. Beto O'Rourke, Vermont Sen. Bernie Sanders, Massachusetts Sen. Elizabeth Warren and businessman Andrew Yang.

Who else -- if anyone -- will join those nine onstage September 12 and 13? The two most likely additional candidates are businessman Tom Steyer and former San Antonio Mayor Julián Castro. Both have met the fundraising threshold, according to their campaigns, and both are just one qualifying poll short of the four they need. Hawaii Rep. Tulsi Gabbard has met the fundraising qualification but has only one poll showing her at 2% or better.

Not making the debate stage, a fate which seems likely for people like Sens. Michael Bennet (Colorado) and Kirsten Gillibrand (New York) may well force tough decisions about how and whether to continue in the race.

1. Warren targets her main weakness: Elizabeth Warren's first attempt to solve the question of her past claims of Native American heritage was a full-blown disaster. (Remember Elizabeth Warren's first attempt to solve the question of her past claims of Native American heritage was a full-blown disaster. (Remember this?) But now, riding high after two strong debate showings and poll numbers that suggest she has moved into second place nationally behind Biden, Warren is taking another swing at tackling the issue -- albeit from a very different direction.

Late last week, Warren released a series of policy plans addressed at the Native American community and she is slated to deliver a major address on Monday in Iowa to a group that advocates for Native American rights. According to CNN's MJ Lee and Greg Krieg , Warren has also done considerable legwork behind the scenes -- meeting with tribal leaders and winning the endorsement of New Mexico Rep. Deb Haaland, one of only a few Native Americans in Congress.

There's reason to believe Warren's second attempt to deal with the Native American question will be more successful than the first -- namely because she is approaching it from the policy side -- consistent with her broader brand as opposed to focusing on her personal narrative.

That's not to say that anything Warren does this week -- or ever -- will stop Trump from using the ethnic slur "Pocahontas" to describe her. But Warren will never convince Trump's base to be for her. She needs to convince Democrats that she can withstand those attacks if she is the nominee.