Key 2020 storylines to watch this week, ranked

(CNN)With 253 days until the Iowa caucuses and a record number of Democratic candidates, the 2020 election is already in full swing. Every Sunday, I will compile the 5 BIGstorylines 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 of the coming week.

5. Happy (almost) Memorial Day! Politicians -- they're just like us! As we all grill out and chow down on ice cream, the Democrats running for president will be doing the same. Literally.
Vermont Sen. Bernie Sanders will host three ice cream social events in New Hampshire on Monday. He'll be joined by a man who knows his way around ice cream: Ben & Jerry's co-founder Ben Cohen. (Cohen is the one of the four co-chairs of Sanders' presidential campaign.)
    Cory Booker ends a four-day Memorial Day weekend swing through Iowa -- via RV! -- with a BBQ in Urbandale on Monday. Delicious!
    He hardly has Iowa to himself, however. At different points in this holiday weekend, his Senate colleagues Kirsten Gillibrand (N.Y.), Elizabeth Warren (Mass.) and Amy Klobuchar (Minn.) crisscrossed the state.
    4. Can Gillibrand make abortion her issue? The New York senator has struggled mightily to distinguish herself amid the crowded 2020 field. Which is why she is placing a very big bet that she can seize on a series of restrictive abortion laws passed in states like Georgia, Alabama, Missouri and Ohio by Republican legislatures to spark her candidacy.
    In Iowa over the weekend, Gillibrand told the crowd at one of her events that "a woman should be able to decide when she's having children, how many children she's having and under what circumstances she's having," according to Politico. She also traveled to Georgia earlier this month to protest that state's fetal heartbeat law, casting the abortion fight as central to American democracy.
    "One of the tenants of our democracy is that we have a separation of church and state, and under no circumstances are we supposed to be imposing our faith on other people," she said. "And I think this is an example of that effort."
    There's no question the push for more abortion restrictions inflames a good portion of the Democratic base. It's less clear if Gillibrand can be the candidate to channel that outrage.
    3.  A majority say they wouldn't vote for Trump: There's a number buried in a Quinnipiac University poll that you should keep an eye on as the November 2020 election gets closer.
    Asked whether they would definitely vote for Trump or definitely not vote for him if he is the Republican presidential nominee in 2020, a majority -- 54% said they would definitely not choose the President. Three in 10 (31%) said they would definitely support Trump while 12% said they would "consider" voting for him. 
    Breaking down that definitely-won't-vote-for-Trump, uh, vote by party: 94% of Democrats said they will not vote for him while 54% of independents and 10% of Republicans said the same. 
    Obviously that looks like a major warning sign for the sitting President. And it is! You never want a majority of Americans saying they absolutely won't vote for you. But remember this: The 2020 election will be a choice between Trump and the Democratic nominee. And the President has to hope that he can convince some of those 54% who say that they won't vote for him that he is the devil they know and, therefore, a safer choice.
    2. Debate season is a month away: One month from today, the first Democratic debate will commence -- the informal kickoff to the long sprint to the February 3, 2020, Iowa caucuses. 
    The debate will unfold over two nights -- June 26 and 27 -- and could feature as many as 20 of the 23 announced Democratic candidates. (At the moment, 19 of the 23 have qualified for the debates -- either by averaging 1% in three national polls or cresting 65,000 individual donors to their campaign.)
    Here's how who gets in which debate will be decided: All candidates polling 2% or higher -- that's Joe Biden, Sanders, Warren, Kamala Harris, Pete Buttigieg, Beto O'Rourke and Booker, according to the Real Clear Politics average -- will be randomly split between the two nights. Then the same wil