President Trump’s tweets about his health-care record Monday were notable for the falsehoods they included, as The Washington Post’s Glenn Kessler noted.

But they were also notable for this: They were in response to a campaign ad for Mike Bloomberg, despite Bloomberg struggling to catch on in the 2020 Democratic race.

Indeed, if you look at Trump’s tweets and comments, you can get a sense for which would-be 2020 opponents Trump is thinking about — and perhaps which ones he fears more than the others.

Trump has privately expressed concerns about the personal war chest Bloomberg might bring to the general election, according to the New York Times. Bloomberg has already spent more than $100 million on ads, and Trump’s tweets — and his relatively frequent comments about him — indicate he’s paying attention despite Bloomberg being an also-ran who isn’t even qualifying for Democratic debates.

When it comes to other candidates, you can sometimes discern such a pattern. Trump frequently boasts he’d be happy to run against many of them. But his words often paint a different picture.

Trump has reserved the largest shares of his comments for Joe Biden and Sen. Elizabeth Warren (D-Mass.).

Biden is the one it’s most apparent Trump would like to avoid; he got impeached, after all, over an effort to get Ukraine to provide ammunition against Biden. Trump’s comments about Biden are almost exclusively derisive, too, calling him “Sleepy Joe” and suggesting he’s fumbling and off his game politically. The combination seems to indicate he’d like to persuade Democrats to go in a different direction in the primary. And it makes sense Trump would want to knock Biden down, given he polls best against Trump in the general election.

With Warren, it often seems to be as much a base play as him trying to attack her. He tries to fire up his supporters by pointing to the liberal Massachusetts senator, whom he almost always refers to by the slur “Pocahontas.” But he has also indicated surprise at her having a fighting chance, telling Nigel Farage in October: “She’s picking up a little steam. I thought she was gone-zo … but she seems to be the one picking up steam, so it could be her.” By December, he again seemed to be paying attention. “I thought I knocked off Pocahontas,” he told a rally in Battle Creek, Mich. “I did it a year too early, a year too early. I give her credit.”

A similar brand of grudging respect came through in his comments about Kamala D. Harris, too, before she dropped out. Trump praised her at the start of the campaign for having the “best opening” and told Sean Hannity in April that “she has got a little bit of a nasty wit, but that might be it.” Trump largely ignored Harris, though, apart from criticizing her for spurning an event with an African American group that had given Trump an award.

Similar to Biden, Trump has suggested he actually wants to run against Sen. Bernie Sanders — however true that is — telling Fox News in May: “I’d like [Biden] to get it. I’d be happy. I’d be happy with Bernie. I personally think it’s those two.” Trump also seems to be paying attention to Sanders’s improving poll numbers in Iowa this weekend, tweeting: “Wow! Crazy Bernie Sanders is surging in the polls!”

Another tweet Monday about Sanders spoke to a real pattern in Trump’s comments about him: He has often tried to use Sanders to divide the Democratic Party. He has suggested Hillary Clinton and the Democratic National Committee rigged the campaign against Sanders in 2016, for example, and he tweeted that Sanders’s supporters were “trashing” Warren because they want her voters.

That gets to another telling pattern in Trump’s 2020 punditry: He often suggests certain things could hurt Biden — perhaps wishfully. He has on multiple occasions returned to the idea that Warren’s and Sanders’s supporters could combine forces if one of them falters.

“When Bernie gets out, it looks like those will go to your radical leftist Elizabeth Warren. Right?” Trump said at a rally in Lake Charles, La., in October. “And that, unfortunately, will be the end of Sleepy Joe, because I would really, probably, most like to run against him.”

He has also said something similar about Bloomberg. “He’s not going to do well, but I think he’s going to hurt Biden, actually,” Trump said in November, when Bloomberg first launched his campaign. Despite Trump assuring that Bloomberg has no chance, he has made a point to criticize him repeatedly for his time as mayor, his personal baggage, his media organization’s decision not to scrutinize his campaign and his campaign ads. Trump’s level of interest in Bloomberg has certainly been greater than other candidates with similar poll numbers (though perhaps that owes in part to his personal familiarity with the former New York mayor).

Pete Buttigieg has also gained Trump’s attention as he gained in the polls in Iowa and New Hampshire. After initially dismissing Buttigieg as having no chance, Trump has been talking about him more. He often talks about him derisively as a lightweight who couldn’t go toe-to-toe with the likes of Chinese President Xi Jinping. The former South Bend, Ind., mayor has even gotten the “I want to run against him” treatment. At a December rally, Trump said: “You know what? I’m not going to say bad things about him. You know why? I’d love him to win.” He added Jan. 3: “I’d like him to win. So, I don’t want to knock — I don’t want to knock these people. … I hope he does great.”

Apart from these comments, Trump has rarely mentioned candidates whom he apparently doesn’t regard as contenders, including Sen. Amy Klobuchar (D-Minn.) and Andrew Yang, as well as Julián Castro, who dropped out this month, and Sen. Cory Booker (D-N.J.), who dropped out Monday. He had occasionally mentioned billionaire Tom Steyer, but not really since Steyer decided to run for president last year.

It’s difficult to draw firm conclusions based on all this when it comes to whom Trump fears most in the general election. Some comments could be reverse psychology, while others could be reverse-reverse psychology. But he generally says he wants to run against candidates for whom he otherwise seems to focus a lot of attention on attacking, which is somewhat counterintuitive. He also regularly refers to the idea that certain machinations could hurt Biden, which feels telling about whether he really wants to run against him. And his comments about the likes of Bloomberg, Buttigieg and Harris have seemed to indicate he has taken them seriously, even if others perhaps haven’t.