Editor's Note: CNN political commentator Robby Mook ran the 2015-16 presidential campaign for Hillary Clinton and is now a senior fellow at Harvard University. The opinions expressed in this commentary are his. View more opinion at CNN.
(CNN) - With the midterms behind us, the 2020 floodgates are about to open. You can expect senators, governors, members of Congress, mayors, movie stars, CEOs (and even a porn star's lawyer?) to start kicking the tires on a presidential run — and announce they're getting into the race.
The one thing we know about the likely candidates is that we don't know anything. It will be the most wide-open field in our lifetime.
After working in the last three competitive Democratic presidential primaries and going through extensive planning and preparation for Hillary Clinton's 2016 run, I'd recommend that candidates consider these five things as they plan:
One: Know why you're doing this -- like, really know
Set a stopwatch for 20 minutes, grab a piece of paper and answer the following questions in no more than three sentences each:
• Why should you be president? • Why should you be president at this point in time? • What's wrong and what are you going to do about it? • Who are you fighting for? • Who are you fighting against?
Did you know the answers? Are they clear and concise? Are they real ideas? Or just a bunch of rhetoric? If the answers to these questions come easily, you have a rationale for running. If not, I recommend figuring them out before you jump in the fray — or maybe it's not your time. And don't try to find any of this in a poll. This part has to come from you.
Two: It's not about you, it's what you stand for
If I'd written a column in November 2014 that read, "In the 2016 primary, a 75-year-old congressman who spent most of his adult life in elected office will emerge as an anti-establishment crusader rallying millennials to his cause," you would have laughed at me. Yet that's exactly what happened.
Bernie Sanders, who had been a member of Congress for 25 years, emerged as an outsider in the race. It's not who you are, but what you stand for that matters. Bernie didn't attract young people because he was young. It was about his ideas.
Your campaign is a vehicle for your supporters to create change and your message is a rallying cry for your cause. Talking about yourself — your accomplishments and the kind of leader you have been — is fine as part of a story that illuminates your values, but your message is ultimately about a diagnosis of what's wrong, a vision of who we are as a country and where we need to go. Many candidates fall into the trap of trying to sell themselves. Instead, sell what you stand for.
Also, ignore the polls right now. When I first arrived in Manchester, New Hampshire, to work for Howard Dean's 2004 presidential bid, one candidate was crushing everyone else in the polls. His name was Joe Lieberman, and we know how that turned out. The polls today are meaningless, so ignore them all. There are way too many unknowns and far too many potential candidates to read much into the data. Plus, your message has to come from you.
Three: This is a change election
The Democratic primary electorate wants change. Some people think that change is represented by certain policy positions, or a particular ideological brand. Not so.
Voters are shopping for a leader, not a litany. They want you to explain where we've been, where we are, and where we can go. They want to hear you explain what's wrong and how we can make it right. They want to know what you think "America" stands for as an idea.
Change is about more than your flavor of Medicare for All or whether you're a "New Democrat," old Democrat, Democratic Socialist, "yellow dog Democrat," "Blue Dog Democrat," or tabby cat Democrat.
In 2008, Barack Obama ran for a new kind of politics that transcended old divides. His positions were oftentimes more conservative than Hillary Clinton's (he opposed an individual mandate, for example), but you don't think of him that way, which is why you shouldn't get dragged down into litmus tests — stick to the "vision thing."
Lastly, your vision of change must be bigger than a rebuttal of Trump's latest tweet. It must be about what America looks like without those tweets altogether. Speaking for yourself and avoiding the trap of litigating the race on Trump's terms will be your biggest challenge.
Four: You are running a national campaign, headquartered in cyberspace
You will sink or swim based on the ability to mobilize fans, who will share your content and donate money. Period. That comes from having an original idea to sell and a top-notch digital operation to push your message out and mobilize supporters. You should also get in front of the press as much as you can. Both Trump and Sanders used cable news appearances in the 2016 race to build their social assets early in the process to great effect.
Gone are the days of sustaining a campaign on $2,700-per-plate chicken dinners at the Marriott. There will be too many candidates and not enough time to raise money the old-fashioned way. Candidates will need a large network of low-dollar donors to sustain them for the long haul.
Also gone are the days of winning one state and "taking off." Yes, it's vital to build a ground game in the early states (and that includes some March states), but camping out in a single state and thinking that can catapult you onto the national stage is outdated. Without generating a fan base, you won't have the resources — money or message — to gain traction and sustain your work.
When I was running Hillary's campaign in 2016, Sanders didn't build out his Iowa operation until very late in the game and quickly pulled the race to a virtual tie. Mitt Romney did not spend a significant amount of time in Iowa, and yet he came in a close second (so close that everyone believed he'd won on caucus night).
Donald Trump's Iowa and New Hampshire operations were a mess, yet he came in second in the Iowa caucus and handily won the New Hampshire primary. You want the best people and the best operations you can in these states, but message travels nationally nowadays -- and it travels fastest via your fans.
Five: You win with delegates
Early in the campaign, what matters is honing your message, building your base of fans and pulling off the strongest possible result in the early states. That foundation makes everything else possible. But what ultimately wins the contest is delegates -- and delegates don't always come in logical ways.
Some candidates get so fixated on the first four states, which have less than 4% of the overall delegates, that they forget to plan and end up short come Super Tuesday. Others fall into the trap of thinking "winning states" is the same as "winning delegates" and it's more complicated than that.
First, the media reports primary contests just like any other election, except they're not. When you see results come in on primary night, they're presented as they would be in any other election contest: Candidate A gets X percent, Candidate B gets Y percent. Then the press celebrates the "winner." But these voting figures are often meaningless and the celebrations are almost always deceptive, because you win the primary with delegates, not votes — and the two are not as correlated as you might suspect.
When I ran Hillary Clinton's 2008 primary campaign in Ohio, we won the state with 53% of the vote, to much fanfare. Obama, who won 44%, trailed by a margin of about 200,000 votes. But we only gained a net of seven delegates over Obama. Compare that to Kansas, where Obama gained a net of 14 delegates with a margin of about 17,000 votes. Clinton won a bigger state with a margin that was nearly 12 times the size, but she got half the delegates. The lesson: Votes do not equal delegates, especially when comparing caucuses and primaries.
You don't even have to win the most votes to get the most delegates. When I ran the Nevada caucus for Hillary in 2008, we "won" with 50.8% of the precinct delegates to Obama's 45.1%, but Obama actually won 13 unpledged delegates -- one more than Clinton's 12 -- because of how the delegates were proportioned by congressional district. Likewise, in 2016, Clinton and Sanders split the delegates in Wyoming evenly 7-7, despite Bernie "winning" the precinct caucuses 55.7% to 44.3%.
Lastly, don't forget the rule that requires Democratic primary candidates to secure at least 15% of the vote in order to win delegates. With such a big field, you'll see a lot of people stall out early because they won't score enough votes to win any.
Only three of eight candidates in the 2008 Democratic primary won any delegates at all -- and John Edwards ended up with less than 1%. Once someone has pulled ahead in the delegate count on Super Tuesday it's virtually impossible for others to catch up, not just because of money and momentum, but because the rules push underdogs out (although with online fundraising, candidates can choose to stay in long after they're not viable).
So never lose focus of what it really takes to win: getting the most delegates.
We say it every four years, but I don't think anyone would disagree -- this really is the most important presidential election in our history — and the playbook will look totally different this time around. But recent campaigns give us some clues as to what contributes to success: an authentic rationale for running, a message that rallies supporters, and fans who are mobilized both on the ground and online. Then, don't forget about delegates. That much we can be certain about; you'll have to figure the rest out as you go along. Good luck!