In this week’s politics chat, we talk about President Obama and his role in the 2016 election. The transcript below has been lightly edited.

micah (Micah Cohen, politics editor): This chat comes to you live from the lobby of the Aloft Philadelphia Airport hotel. Today’s topic: President Obama, who speaks to all the assembled delegates and media at the Democratic National Convention tonight. Two main questions for your consideration today: 1. Obama’s approval rating has been rising — why? 2. What effect will Obama have on the race? (And what effect do incumbent presidents have on open races generally?)

Let’s start with Obama’s increasing popularity. This chart from RealClearPolitics shows Obama’s approval (black) and disapproval (red) ratings:

What are the prevailing theories as to why Obama’s approval rating is up? (Also, side note: Harry is traveling while we do this chat so will only be participating sporadically.)

harry (Harry Enten, senior political writer): The main theory: Voters dislike Hillary Clinton and Donald Trump, so Obama looks better by comparison.

clare.malone (Clare Malone, senior political writer): Yeah, the specter of both Trump and Clinton — people are realizing how good they have it. Harry and I are on same page.

natesilver (Nate Silver, editor in chief): How confident are we about that theory? I mean, it’s intuitively compelling. But maybe Obama’s approval rating is ticking up for other reasons? The economy isn’t bad? He seems to pivot reasonably well off a GOP Congress? People are feeling sentimental since his term is about to end?

I will acknowledge that the shifts line up reasonably well with when it became clear that Trump and Clinton would become their respective party’s nominees.

micah: Do presidents’ approval ratings typically go up near the end of their second terms?

natesilver: They typically go up VERY late in the second term — like, once they become a lame duck. A little early for that now, though.

micah: I find the comparison to Trump and Clinton theory pretty compelling, especially because other events on the world stage haven’t exactly been morale-boosting.

clare.malone: Occam’s razor — isn’t that what it is, Nate? Clinton/Trump making him look better? (I’ve been here long enough that now I’m using all these stupid buzzzzzz terms.)

natesilver: Well, the contrast with the right track/wrong track numbers, which are bad, is pretty striking. “We think the country is going to hell BUT we sorta like that Obama guy!”

harry: Yeah, but those right track numbers have been bad for a while.

natesilver: It’s also become sort of politically convenient — on both the left and the right — to say the country is in decline. Pessimism sells. Which is not to say the United States doesn’t have VERY profound problems. But if you ask people about their personal circumstances, they feel a lot better than if you ask them about how everyone else is doing.

micah: Clare, in your reporting at Trump rallies and Clinton events, does Obama ever come up when talking to people?

clare.malone: Obama came up a lot more when people like Ted Cruz and Marco Rubio were in the race. Those guys were talking a whole lot more about how they thought that Obama was trying to adversely change American society. Trump talks just a ton about Clinton and honestly not that much about Obama these days (save for today).

natesilver: Which is why it will be interesting to see how much Obama takes on Trump tonight.

micah: Yeah, so let’s get to that: What do you expect from Obama tonight?

clare.malone: I think he’s going to basically say, “I know this job and all its perils and moral decision-making, the stresses, the seriousness of it — Donald Trump has not shown he is a serious person, a person intellectually up to the job.”

He’s going to make the qualification argument against Trump, whereas Michelle Obama made the ethical argument against Trump.

natesilver: As is true for most of these speeches, there are four basic directions he could take: (1) praise Clinton, (2) articulate Democrats’ values, (3) talk about how the country is making progress, (4) slam Trump.

So far, we’ve seen a lot of No. 1 and No. 2 at the convention. Which means Obama — and Joe Biden — might be more inclined to No. 3 and No. 4. It would be quite dramatic if Obama REALLY laid into Trump. Probably unusual for a sitting president to do that, although I’d need a historian to confirm that. And he has to avoid violating Michelle Obama’s credo of “when they go low, we go high.”

So it’s a high-stakes speech. I can see a universe in which Biden really goes after Trump and Obama is more subdued. It does seem a safe bet that SOMEONE is going to have to give the rip-Trump-to-shreds speech at some point, à la what Chris Christie did to Hillary Clinton. I just don’t know if it’s going to be the POTUS.

micah: I don’t think it will be Obama.

harry: I wouldn’t be surprised if it were Biden.

clare.malone: Obama doesn’t have to say Trump’s name to attack him. He could talk about the weight and seriousness of the office — people get the point, I think. Our brains haven’t turned all to Pokemon mush just yet.

micah: Give it time.

natesilver: I think the over-under line is that it will contain a few very pointed lines of criticism about Trump. A little could go a long way.

micah: Let’s zoom out for a second, beyond tonight’s speech — what effect do incumbent presidents have on open races?

Isn’t there some David Axelrod quote where he says every election is a referendum on the incumbent president?

natesilver: We don’t know because there have been only four term-limited presidents in the history of the United States. Five, counting Obama.

Obviously, you’d rather have the incumbent president be more popular than not. But it isn’t a 1-to-1 relationship. Bill Clinton had a better approval rating in 2000 than Reagan did in 1988. But George H.W. Bush won big, whereas Al Gore lost (err … tied, basically).

clare.malone: I remember having a conversation in a car in Iowa about whether Obama would have won the 2016 election if he were allowed to run. I think we decided he had a pretty good shot. While there might not be hard evidence, the fact that Hillary Clinton is standing on the shoulders of a fairly successful administration helps her, at least in the very specific case of 2016, when a lot of people don’t personally like the candidate running on the incumbent party’s ticket.

natesilver: There’s a contrarian case to be made that Obama’s approval ratings are improving precisely because he’s leaving the partisan fray … and that wouldn’t be true if he were eligible (and running for) a third term.

In fact, there’s a whole contrarian case to be made that Clinton’s unpopularity is a result of circumstances that might have affected any Democratic nominee and aren’t all that personal to her.

But … I don’t know. I tend to think Obama would wipe the floor with Trump.

micah: But Nate, isn’t the incumbent president’s approval rating really predictive?

natesilver: It’s really predictive when the incumbent is running for re-election. It’s moderately predictive when the incumbent isn’t.

micah: Trump, in a news conference in Florida going on as we chat, just called Obama “the most ignorant president” in American history.

natesilver:

Trump: 'I think President Obama has been the most ignorant president in American history.' — Byron York (@ByronYork) July 27, 2016

I mean, from a Politics 101 standpoint, this is dumb. It’s possible that Trump is more popular — or less unpopular — than Clinton. He’s much less likely to win a popularity contest against Obama.

micah: That’s the thing. Part of this convention seems like presenting the race as the Clintons and the Obamas vs. Trump.

clare.malone: Hah.

micah: Oh, and Tim Kaine.

clare.malone: Poor Tim Kaine — no one’s paying him any mind. I guess that’s the point.

micah: Yeah, I don’t think the Clinton campaign is necessarily unhappy with that.

All right, next topic: Has the 2016 race generally, and the conventions in particular, made you re-evaluate Obama’s tenure? Re: our first question, it seems to have for the American people.

natesilver: My instinct, especially if you also look at what’s going on elsewhere in the world, is that it seems more remarkable that Obama was able to hold things together.

micah: Expound on that. Hold what together?

natesilver: For one thing, the Democratic coalition. Obama is one of the things that unites the Clinton and Sanders wings of the party.

But for another, playing a long game, and being a calming influence, instead of being overreactive.

Obviously Obama’s critics would call that a lack of leadership, and I’m probably revealing my biases here.

clare.malone: Here’s the one thing I keep on thinking about vis à vis Obama and the moral authority of a president and who is fit to hold the office: executive orders and executive actions.

It’s no secret that because he faced a recalcitrant Congress, Obama took a lot of executive actions. He was also a president famous for making a “kill list” for terrorists that seemed to many to operate outside the bounds of what many were previously constitutionally comfortable with. With Trump on the scene, with his recent comments about Russia and NATO, I have been thinking about the precedent that Obama set when it comes to executive actions.

What kind of actions would Trump take as president? Obviously, the Republicans have bemoaned Obama’s unilateral decision-making, but politics is all about using what’s expedient — once you’re in office and your predecessor has set a precedent, there’s very little to stop you from using it to your own ends.

micah: And that goes to Nate’s point about Obama holding things together — there are a lot of people, I imagine, who are fine with Obama doing those things who would not be fine with Trump doing the same, or even Clinton.

harry: People like Obama in ways they never liked Clinton. People trust him.

clare.malone: Yeah, and I think that’s the problem of Obama setting this precedent in a democracy — not all leaders are alike or as trusted. The system was put in place to guard against the misuse of power. Consolidation of power into anyone’s hands, even hands we trust at any given moment, should be seriously thought about.

That’s not a question of politics, I don’t think. It’s more about political philosophy, but man, political philosophy is lived by a person who holds the highest office in the land.

natesilver: Many, many people in the country don’t trust Obama. But in comparison to Trump or Clinton? They think he’s St. Francis. They think he’s basically acting in good faith.

micah: What are Obama’s trust numbers, Harry?

harry: Obama has generally been trusted even when his approval rating has been down.

clare.malone: Yeah, but same thing, Nate — good faith or trust. Obama has in many ways fundamentally changed the way a president acts in modern war and in some cases, on the domestic policy front. That is existentially troubling. (I say “existential” too much this year, but man …)

I’ve been living in one variety or another of a Potemkin village for the past 10 days. I’m feeling gnarly and existential and reflective, man.

natesilver: I think the country could really use three weeks off to watch the Olympics, or whatever. But I get the feeling it will be as crazy as ever.

micah: All right, final question. It’s fill in the blank: “Without Obama, Hillary Clinton’s support (currently about 41 percent in national polls, according to our polls-only model) would be ___ percentage points lower.”

In other words, does Obama matter on the margins? Or is he like super-important for Clinton?

natesilver: Ehh. I know where you’re going with that, but it’s a weird question.

My general view is that Obama’s influence is mostly priced into Clinton’s numbers at this point. In other words, I wouldn’t necessarily expect her numbers to improve just because Obama is more popular than she is.

But there’s one exception, I think, and that’s with Sanders voters.

clare.malone: Nate, you must be really bad at Mad Libs. This is a long fill in the blank.

natesilver: Clare, I don’t like to reduce everything to numbers.

clare.malone: Right, that’s just me. I apologize. Carry on — don’t let Micah box you in!

harry: I think if Obama’s approval were 5 points lower, Trump would be leading in all our models.

clare.malone: Huh. She’s living on that much of a razor’s edge?

harry: Yes.

natesilver: But is Obama’s approval rating a cause or an effect of political conditions? That’s why I think it’s weird to consider the president’s approval rating to be a “fundamental” variable, which is somehow detached from the horse race.

micah: OK, we gotta wrap.

clare.malone: So I guess you’re not getting an answer to your question, Micah. It’s an unknown unknown.

micah: I never get what I want.

clare.malone: NO, a known unknown. It’s unknowable. Whatever.

natesilver: Look, tonight’s speech is really important. If Obama’s approval ratings help Clinton, this convention is when she’s gonna get that help.

micah: That’s a good place to end.