President Donald Trump bashed Democrats as the "party of socialism, late-term abortion, open borders and crime" in a red-meat rally that previewed where he's likely to head as he tries to win a second term. Trump also blasted the man who once represented El Paso in Congress as "a young man who's got very little going for himself, except he's got a great first name."

That "young man" -- former Rep. Beto O'Rourke -- was headlining a rally to protest Trump and his policies. "We are the example that the United States of America needs right now," O'Rourke told the crowd. "This is where we make our stand!"

It was the clearest sign yet that the man who became a single-named national phenomenon in his ultimately unsuccessful 2018 campaign against Republican Sen. Ted Cruz was actually getting ready to run in 2020 -- and that the current resident of the White House was paying very close attention.

For 2020 Democrats not named "Beto," Monday night's back and forth had to be a humbling affair. It made clear not only that O'Rourke has star power and a grassroots backing that is the envy of the Democratic Party but that Trump himself is already elevating Beto with his attacks.

Monday drove home a simple reality: If and when -- and it feels more like a question of when than if at this point -- O'Rourke decides to get into the 2020 race, he will fundamentally alter the contest in ways big and small.

O'Rourke, possibly more than any other candidate -- up to and including former Vice President Joe Biden -- will become the central mover of the contest. He will act, others will react.

Below, our latest rankings of the 10 Democrats most likely to wind up as the party's nominee next fall.

10. Sherrod Brown: The case is easy to make for the senior senator from Ohio. The case is easy to make for the senior senator from Ohio. Electability is key for Democratic voters in 2020 , and Brown just won re-election by 7 points in a state Hillary Clinton lost by 8 points. Unlike other candidates, (see Biden, Joe), Brown likely won't have to go on apology tour for previously held conservative positions, given that he voted against the Defense of Marriage Act in 1996 and the Iraq War in 2002. So what is Brown's problem? There will be other candidates who can argue they're electable, and others who will say they're liberal. We're also just not sure the party will nominate a white man. Brown would, however, likely move up in our rankings if he decides to officially run.

9. Kirsten Gillibrand: The New York senator is still in the exploratory phase of the race although she is quite clearly running. Her early state visits to date have The New York senator is still in the exploratory phase of the race although she is quite clearly running. Her early state visits to date have shined a light on how her record as a member of the House was considerably more conservative than she currently portrays herself. Explaining that delta is central to Gillibrand's ability to sell herself to voters. Right now, she is lagging a bit because she simply isn't as well known as some of the other candidates in the race.

8. Julian Castro: A big problem for a lot of 2020 contenders is making their resume stand out. That currently isn't a problem for Castro. He's never served in Congress, which you can't say for most other candidates in the race. Castro's the only Latino running (Latinos made up 18% of Democratic voters in 2018, A big problem for a lot of 2020 contenders is making their resume stand out. That currently isn't a problem for Castro. He's never served in Congress, which you can't say for most other candidates in the race. Castro's the only Latino running (Latinos made up 18% of Democratic voters in 2018, according to Pew Research Center ), and he has a good biography to boot. The most obvious problem for him: this field is full of bigwigs, so folks with minimal name recognition will have some difficulty standing out. Additionally, this race likely isn't big enough for two Texans, and O'Rourke may steal Castro's thunder if he enters.

7. Amy Klobuchar: The optics of the Minnesota senator's The optics of the Minnesota senator's formal announcement last weekend couldn't have been better -- she touted her grit and toughness while something close to a blizzard went on all around her. Klobuchar's announcement was somewhat marred, however, by a series of stories that painted her as a very difficult boss (and that's being nice). Assuming she can find a way past those stories, Klobuchar's focus on her Midwestern roots should position her well to make a serious run in Iowa.

6. Bernie Sanders: Vermont's junior senator is second in the polls, and no candidate had a better ratio between his very favorable and somewhat favorable rating in our December Iowa poll (i.e. the people who like him really like him). That could matter in a field where a lot of candidates will likely be running. Like Brown, few can argue against the idea that Sanders was liberal before it was cool. It's not clear, however, that Sanders can pick up support beyond his base. He continues to poll well behind his 2016 primary showing despite having high name recognition. Sanders is an independent running in a Democratic Party with other actual Democrats who are also very liberal. Finally, many Clinton fans still have Vermont's junior senator is second in the polls, and no candidate had a better ratio between his very favorable and somewhat favorable rating in our December Iowa poll (i.e. the people who like himlike him). That could matter in a field where a lot of candidates will likely be running. Like Brown, few can argue against the idea that Sanders was liberal before it was cool. It's not clear, however, that Sanders can pick up support beyond his base. He continues to poll well behind his 2016 primary showing despite having high name recognition. Sanders is an independent running in a Democratic Party with other actual Democrats who are also very liberal. Finally, many Clinton fans still have ill will toward him after 2016

5. Cory Booker: The New Jersey senator is -- with the possible exception of O'Rourke -- the most naturally gifted candidate in the field. Booker is a charismatic speaker and will undoubtedly light up rooms in Iowa, New Hampshire and South Carolina. The question is: what is Booker selling? The New Jersey senator is -- with the possible exception of O'Rourke -- the most naturally gifted candidate in the field. Booker is a charismatic speaker and will undoubtedly light up rooms in Iowa, New Hampshire and South Carolina. The question is: what is Booker selling? His announcement in Newark earlier this month leaned heavily on his personal biography and his message of love and unity. Is that enough?

4. Elizabeth Warren: If you If you look at the polls , Warren is in second place among those who have declared their candidacy. The attacks from Trump on her lack of Native American heritage may actually work to Warren's benefit, if Democrats rally around her. In her perfect universe, Warren will rally those on the left, while also being reassuring to those in the establishment who are afraid of Sanders. Warren's flaws are fairly obvious: she may be too far left for Democrats who want a more moderate candidate, and her lackluster performances versus the average Democrat in her Senate runs may be a huge issue for voters who are prizing electability.

3. Beto O'Rourke: It's hard to imagine this week going any better for Beto. Not only did he hold a large rally opposite Trump in El Paso but the commander-in-chief repeatedly went after him It's hard to imagine this week going any better for Beto. Not only did he hold a large rally opposite Trump in El Paso but the commander-in-chief repeatedly went after him in the course of a 75-minute speech . It's hard not to see O'Rourke running at this point but he is expected to make a final decision by the end of the month . Assuming he runs, the first few months of his campaign are critical; how much of the buzz and excitement that still clings to him -- despite losing a Senate race in 2018 -- can he translate into money, activists and poll numbers?

2. Joe Biden: There is perhaps no candidate who we are more unsure of than the former vice president. Biden leads in all the polling and matches up well with what factors voters say are important in determining their 2020 selection. Biden is also likely to pick up a slew of endorsements from election officials, which is usually correlated with success. Still, we wonder whether Biden's support would fall apart if he ran. Much of it may merely be goodwill leftover from when he was President Barack Obama's No. 2. Goodwill that may disappear when he is attacked over his fairly moderate record. We're also at least somewhat doubtful that a party base that despises the current President will nominate its own older white man to be Democrats' standard-bearer.