(This is the ninth edition of our monthly power rankings of Democrats most likely to get their party's presidential nomination in 2020.)

(CNN) Since Monday, four candidates have made their final go/no-go decisions about the 2020 Democratic presidential race.

Washington Gov. Jay Inslee is in. Former Attorney General Eric Holder, former New York City Mayor Michael Bloomberg and Oregon Sen. Jeff Merkley are out.

And the 2020 election is only 607 days away!

The rapid-fire decisions made by that quartet of candidates speaks to how quickly the 2020 race has gone from a standstill to a dead sprint. The battle for key early-state operatives is on. The fight for online dollars is joined. And any candidate not in the race by now runs the risk of getting lapped.

There are two exceptions to that rule: Joe Biden and Beto O'Rourke.

Biden remains the poll frontrunner due to his residual name ID from eight years as vice president and four decades in the Senate. He keeps inching ever closer to the race -- he said last month in Delaware that the "most important people in my life want me to run" -- but hasn't officially jumped in yet. At this point, Biden's official announcement feels like a formality. He's running, the only question is how he will run.

While O'Rourke is on the other end of the political experience spectrum from Biden, he, like the former VP, can afford to wait a little while longer before making his plans plain because of his national celebrity. O'Rourke became the Democratic golden child during the 2018 campaign and even though he didn't beat Republican Sen. Ted Cruz in Texas, the shine apparently has not worn off. O'Rourke, like Biden, seems to be an all-but-announced candidate. The question is whether the energy he built behind his Senate candidacy in Texas can be replicated -- or even approximated -- at the presidential level.

Below, our rankings of the 10 candidates most likely to wind up as the Democratic presidential nominee against Donald Trump in November 2020.

OUT: Sherrod Brown: The Ohio senator was originally ranked at No. 8 on this list before he announced Thursday that he will not run for president in 2020. The updated rankings are below.

10. Jay Inslee: With Brown out, the Washington governor is in. Inslee recently announced for president and made clear that he is running as, basically, a one-issue candidate -- seeking to draw attention to what he believes is the urgent crisis of climate change. Inslee has an intriguing resume -- he spent time in Congress before being elected governor -- but it's not yet clear if his climate change focus will be enough to distinguish him in the already crowded field. (Previous ranking: Unranked)

9. Kirsten Gillibrand: The case for the junior senator from New York remains the same as it's always been. She's got the most anti-Trump record of any senator and is running in a primary in which voters strongly dislike President Donald Trump. We're also of the belief that Democrats want to nominate a woman (e.g. 91% of Democrats said they would be comfortable or enthusiastic about nominating a woman in the latest NBC News/Wall Street Journal poll). Gillibrand, though, just hasn't caught on yet. Her poll numbers for the Democratic nomination remain in the low single digits. Charges of flip-flopping dog Gillibrand's campaign. It's not clear that Democrats have any interest in her given they have a wide variety of choices. (Previous ranking: 9)

8. Julian Castro: Of the major announced candidates, Castro, the former mayor of San Antonio, is the only major Latino candidate in the race. That's not insignificant, given the rising political power of the Hispanic community -- particularly in Democratic politics -- and the centrality of the immigration issue in Trump's presidency. (Castro is already seeking to organize Hispanic voters in Iowa in advance of the state's first-in-the-nation caucuses.) Castro's argument that he is the strongest candidate against Trump revolves around the notion that he can win Florida, Arizona and Texas due to his appeal to Hispanics. His is an intriguing candidacy though, realistically, he's likely running to be VP rather than for the top spot. (Previous ranking: 8)

7. Elizabeth Warren: When the Massachusetts senator, finally, officially entered the race last month, there just wasn't all that much buzz around her candidacy. She raised around $300,000 in her first day as a candidate -- a total that paled in comparison to the stunning nearly $6 million Sen. Bernie Sanders (I-Vt.) collected in his first 24 hours in the race. And since Warren has been running, she's struggled to draw much attention. That may -- emphasis on may -- be part of Warren's plan, given how badly she botched her attempt to put questions about her Native American heritage behind her last fall: Lay low and wait for things to settle. (Previous ranking: 4)

6. Cory Booker: New Jersey's junior senator polled as well in February as O'Rourke. He may have more potential support in the endorsement primary than all but Harris. Booker's play as a healer sets him apart from the rest of the Democratic field and may actually be what Democratic voters want. His launch generated more Google searches than all but Harris and Sanders. Democratic voters are more enthusiastic or comfortable nominating an African-American than someone matching any other attribute. Yet, Booker hasn't caught fire. He remains well in back in polls of folks like Biden, Harris and Sanders, even though he's been running for over a month. We continue to ponder whether charges of being a neoliberal will hurt him, and whether his passion sometimes comes across as overdramatic. (Previous ranking: 5)

5. Amy Klobuchar: Klobuchar's announcement in a near-blizzard was epic -- and very, very memorable. Unfortunately for her, the early days of her candidacy have been defined by a series of stories about her bad treatment of staff. (Also, she ate a salad with a comb once.) Assuming that story line has run its course -- and there haven't been any flare-ups in the last few weeks -- then the Minnesota senator should be fine going forward. Her focus on grit as her strongest attribute and her Midwestern roots should play well in Iowa where she must perform well to have a serious chance at the nomination. (Previous ranking: 7)

4. Beto O'Rourke: We know an announcement of some type regarding a presidential run is coming soon from the man simply known as "Beto." We wonder whether O'Rourke will be able to recapture the excitement on display during his Senate bid. His appeal was not ideologically based, which could help him unite the different parts of the Democratic Party. O'Rourke demonstrated a unique ability to raise a lot of money in 2018. Since then though, things have cooled off. He's dropped from an average of 13% in national polling in December to only 5% in February. Other candidates have entered the race and have commanded a lot of media attention. Until he runs, we're in a holding pattern. We recognize that O'Rourke has shown ability to connect with Democrats, but we want to see if he can do it again. (Previous ranking: 3)

3. Bernie Sanders: We've been notably skeptical of Sanders in these rankings -- driven by a belief that the success of his 2016 campaign was fueled, in large part, by the fact that Hillary Clinton ignored him and never laid a glove on him. While we still think there is truth to that argument, and that 2020 is a totally different race for Sanders, it's impossible to ignore the grassroots energy that exists for him. One example: Sanders raised almost $6 million in the first 24 hours of his candidacy, an absolutely eye-popping sum. Sanders has what other candidates all want (and need): Organic grassroots energy for his campaign. (Previous ranking: 6)

2. Joe Biden: No one confounds us more than the former vice president. Biden continues to lead national polling and has strength in all the early states. Polling indicates that many of the qualities voters are looking for fit well with Biden's resume. He can probably pick up a number of endorsements when he declares. Importantly, there are more and more signs Biden will actually run. Biden, though, has weaknesses. He has a long record that can easily be attacked. Democratic voters are not enthusiastic about nominating someone over the age of 75. He could also be stale from not having run a campaign for a long time. We wonder how much of his polling advantage will evaporate once he is no longer just President Barack Obama's vice president and he is his own entity. (Previous ranking: 2)

1. Kamala Harris: The California senator has held down the top spot in our rankings for five straight months now. She continues to run a practically flawless campaign, a hard thing to do for someone who is doing this for the first time. The only potential hurdle for Harris is the nominating calendar; if she doesn't win, place or show in Iowa or New Hampshire, does that make her less viable in her must-win state of South Carolina? If she can make it that far, the map gets friendlier, with the massive treasure trove of California's delegates waiting in early March. (Previous ranking: 1)

UPDATE: This story has been updated.