Throughout this primary season, I’ve had an ongoing fight with a co-worker about whether Donald Trump could win the general election. I was pretty firmly in the “if the economy collapses, maybe, but he is much more likely to drag the entire Republican field down with him” camp.

To resolve this, my co-worker invited me to set up some benchmarks: what we would have to see in order to believe that Trump really could win the election – not just that he had some sort of outside shot in a perfect storm, but that he had a legitimate, realistic chance of winning.

To cover my bases, I tried to set benchmarks that I thought would be really difficult for Trump to meet: He would have to pull within five points of Hillary Clinton in the RCP Average within a month of wrapping up the GOP race (this was back when he was down by 10), and then he would have to prove that he could lead her in a polling average (rather than in the occasional outlying poll) by the end of the Republican convention.

So, here we are. Last week, Trump was up by 0.2 percent in the RCP Average, meeting both of my goalposts two months ahead of schedule. I still believe that he is the underdog, but I have to concede that he can win. I would put his chances more around 30 percent today. If at some point he establishes a durable lead (he returned to trailing Clinton Friday morning), or if he can push his average up into the high forties, I will revise things accordingly.

Why might this continue? Here are a five reasons:

1. Their unfavorables cancel out.

For much of this campaign, we’ve focused relentlessly on Trump’s high unfavorable ratings. This is appropriate, given that he has the highest unfavorables of any presidential nominee in years for which we have data.

What’s received far less attention is that he is running against the nominee with the second-highest unfavorables of any presidential nominee in years for which we have data.

This gap also has been shrinking. Trump’s average rating runs 35.2 percent favorable and 58 percent favorable. Clinton’s are 36.3 percent favorable and 56.3 percent unfavorable. That’s not a huge difference.

Even if we take into account individual polls showing higher spreads, we might ask ourselves “Does this really matter?” and reasonably conclude, “No, it does not.” Think of it this way: Assume that the base for both parties is about 40 percent of the electorate. You can make a case for it being a bit larger or a bit smaller, but just assume this is where “yellow dog Democrats” and their Republican counterparts begin.

If this is more or less correct, then Clinton and Trump probably have maxed out their unfavorables among opposing partisans, among Independents, and are now cutting into his/her own base. But these voters will ultimately hold their nose and vote for their candidate (witness the ever-shrinking faction of #NeverTrump voters on the Republican side, and the fact that Trump’s -- and Clinton’s -- vote shares are considerably higher than their favorables). I’m not saying this makes no difference, as voters can stay home. I’m just saying both Clinton and Trump are probably past the point where they receive a diminishing penalty for their unfavorable ratings.

If you’re still unconvinced, think of it yet another way: If the 2004 presidential election had been held when George W. Bush had a 90 percent job approval rating, it is unlikely he’d have received anywhere near 90 percent of the vote. We can be reasonably certain about this, given Franklin Roosevelt’s re-election results with job approval ratings north of 70 percent.

2. Candidates don’t matter much.

Taking this a step farther, it is almost axiomatic among political scientists that candidate effects don’t matter much. That’s not to say they don’t matter at all, just that they are overstated. When I built my Senate model several years ago, I found that controversial candidates like Christine O’Donnell and Ken Buck probably only cost Republicans a couple of points (O’Donnell’s vote share actually closely mirrored the president’s unfavorable ratings). What you’re basically left with are what we call “fundamentals”: job approval, economic growth, and the like.

Right now, the fundamentals point to a close race: President Obama’s tepid job approval combined with mediocre economic growth and second-term fatigue probably create a roughly even playing field between the parties. The polling right now actually reflects that more closely than the polling from a month ago did.

3. Trump might do better with nonwhites than you think.

My operating assumption has long been that Trump would run about as poorly as John McCain and Mitt Romney among African-Americans, and also would run significantly worse among Hispanics. This would require Trump to secure about 64 percent of the white vote in order to win – a tough haul. But Trump’s numbers among nonwhites have actually been relatively decent. If we assume that undecided voters are ultimately representative of decided voters (within groups), Fox News has him winning 7 percent of African-Americans and 27 percent of Hispanics – roughly Romney’s showing in 2012. ABC News has him winning a little bit more than 20 percent of the nonwhite vote – a bit better than Romney (Fox News also has him eventually winning 64 percent of the white vote).

This has led some to question the accuracy of these polls. You can (and should) read a more fulsome response from Jon Cohen and Mark Blumenthal of SurveyMonkey here, but I’ll just fall back upon a saying from one of my favorite law professors: When someone’s argument boils down to “it cannot be,” it means that it probably is.

Furthermore, it’s entirely possible that the media’s single-minded focus upon Hispanics as immigration reform advocates is simply wrongheaded. I’ve written about this at much greater length here and here, but it could be the case that Romney’s showing in 2012 represents a floor, that immigration isn’t as high-salience an issue among Hispanics as many assume, that some of Trump’s appeal to working-class whites translates to working-class Hispanics and African-Americans, and that he will perform surprisingly well (or at least surprisingly not poorly) on Election Day.

4. Both candidates have room to grow.

The common rejoinder is that these polls represent the state of the race with Trump having wrapped up the Republican nomination, while Clinton is stuck in a nasty race with Bernie Sanders. Once she nails down the nomination, the race should shift back to her (under this argument).

First, I’m not entirely certain the assumption that she will win over all of the Sanderistas is correct. While she will certainly win the overwhelming majority of them, Trump’s strategy for this election – coming at the traditional right/left line orthogonally on issues like trade and foreign policy – could result in some of these voters backing Trump; we would expect these voters to be disproportionately represented in the ranks of people resisting Clinton today.

But more to the point, the ABC News poll finds that Trump is, in fact, pulling in 11 percent of Democrats to Clinton’s 8 percent of Republicans, but that only 3 percent of Democrats are undecided, while 7 percent of Republicans haven’t made up their minds. The Fox News poll has similar findings, with Clinton and Trump both taking an equal number of voters from the other party, and showing a similar number of undecided partisans.

You may say “Sean, Sanders’ supporters aren’t Democrats. They’re independents.” Fair enough. One way to get at this would be to look at ideology, since they are presumably self-described liberals. The Fox News poll shows Trump winning 12 percent of liberal voters, while Clinton wins 13 percent of very conservative voters and 27 percent of somewhat conservative voters, and similar numbers of undecided voters. The ABC News poll shows Trump doing a bit better among liberals than Clinton is doing among conservatives, but this is offset by the fact that there are more liberals than conservatives in the poll.

In other words, there is probably room to grow for both Clinton and Trump. We can debate whether more liberals will come home to her than conservatives for Trump, but it isn’t an open-and-shut case.

5. Hillary Clinton is a bad candidate running a bad campaign with bad commercials.

It’s no great secret that Clinton isn’t a natural politician. What’s been more surprising to me is how bad her campaign has been run. Part of this is that it is still early; Team Clinton is probably still feeling Trump out.

But part of it is probably that Team Clinton is experiencing the frustrations that the various Republican campaigns encountered in the winter and fall: Trump is a tough candidate to run against because he doesn’t fit into the typical categories.

Think of it this way: From 1968 to 1988, Republicans basically ran cookie-cutter campaigns against their Democratic opponents: They are liberal. It worked magnificently, until 1992, when they suddenly encountered a candidate against whom the shoe didn’t really fit. Democrats moderated their positions on certain issues and flipped the narrative. For the next 20 years, the generic Democratic campaign became one where Republicans were depicted as agents of the rich, of social conservatives, and of reckless foreign policy adventurists. It was effective, in part because the shoe often fit.

It’s become obvious that, at least for now, Clinton is running the same sort of campaign against Trump. It isn’t clear, however, how well it works against someone with such a strong nouveau riche affect (at best). Trump isn’t campaigning (anymore) on massive tax cuts for the rich. He’s against free trade, and is arguably more of a dove on foreign policy than Clinton. And the two obvious themes against Trump -- that he doesn’t know what he’s doing/is erratic/is inconsistent and that he is actually a right-wing ideologue – are actually in tension with each other. Because Trumpism is such an odd mishmash of beliefs, it’s hard to run the generic Democratic campaign against him.

Even the details of the Clinton campaign have been off. This started with her launch, but has continued into the advertising. Tom Edsall has an excellent piece describing an advertisement hitting Trump on his comments about women, but also explaining how it falls flat, especially among men. Her “woman card” response – e-mailing woman cards to supporters – was odd. I thought the point was that there wasn’t a woman’s card to play?

Other advertisements have been problematic, from the one asserting that Trump always keeps his promises (a key attribute for non-ideological undecided voters) to another that features a flat-toned, emotionless, near-scowling Clinton making pronouncements against Trump that would instead appeal to a wide range of the electorate (the public is actually favorably inclined toward requiring citizens to learn English and, much as I hate to say it, the use of waterboarding). Again, part of this is just the difficulty running against a malleable candidate without a voting history.

Finally, it isn’t clear how well equipped the Democrats are to handle an all-out beer house brawler like Trump. Every utterance of “surely he won’t go there” has been proved wrong. The instinct that this will catch up with him eventually is a tempting one, but at this point, an awful lot of what we might call the “OMG Trump” reaction is baked into the existing numbers.

Again, none of this should be taken as a prediction of a Trump victory. There’s a fair amount of devil’s advocacy built into the foregoing. But I can’t say, objectively, that he’s a heavy underdog anymore.