At the moment, Hillary Clinton's lead is just shy of her biggest margin since Donald Trump locked up the Republican nomination in early May. She's up by 7.7 points in the RealClearPolitics polling average, down a fraction from the peak of 7.9, which was recorded on Tuesday.

Trump's problem in the polls has been that he can't seem to get out of the low-40s. After the Republican convention, he broke past 45 percent in the polling average for a day or two, but that quickly collapsed. Now he's back down at 40 percent or so. Clinton, for her part, has been above 43 percent in the average every day since May 1. Trump has been above 43 percent for 12 days. The methodology doesn't really matter here: In internet or in live-caller polls, Trump's in the same trough.

The question for his campaign should be, "How do we appeal to new voters?" (Which is a much better question to face than, "How do we explain our candidate's suggestion that 'Second Amendment people' deal with judicial appointments in a Clinton administration?") He spent four days trying to do that at the Republican convention, with the net result that more people said they were less likely to vote for him when it was over.

Clinton's drop from a 7.9-point to a 7.7-point lead is in part a function of a new poll from Bloomberg, showing Clinton with a 6-point national lead. In most cases, that's bad news for the trailing candidate, but after a spate of polls showing Trump down by double-digits, being down by only six is probably somewhat refreshing.

As we've seen with other post-convention polls, there's a split on why people support Clinton or Trump. Clinton backers are more likely to plan to vote for her because they like her as a candidate. Trump backers are more likely to say he has their vote because they don't want Clinton to win. This refrain isn't limited to regular voters, of course. In the victory speech he gave after winning his primary on Tuesday night, House Speaker Paul Ryan skipped over talking about Trump instead reminding listeners that they need to go out and stop Hillary Clinton.

The problem with that is that it suggests Trump himself doesn't have much appeal beyond his core base of support. About four-fifths of the supporters for both Trump and Clinton says they won't change their minds. But Clinton has an edge in the question of enthusiasm, with 62 percent of her backers saying they're very or fairly enthusiastic about her candidacy. Only 55 percent of Trump's backers say the same thing.

This number should be more alarming to Trump, though: Bloomberg asked people if they would consider voting for the other candidate. More than half -- 51 percent -- said that they could never support Donald Trump. That's more than 9-in-10 of those who weren't currently supporting him. By contrast, 44 percent said they could never support Clinton, a little less than 9-in-10 of those who didn’t plan to vote for her.

Clinton's not doing fantastically, mind you, but as long as she continues to lead in the polls, she's not the one that needs to grow her base of support.

Compounding the problem for Trump is that his allies are also less popular than Clinton's. Neither of the two front-runners is very popular, though Clinton is now viewed a bit more favorably than is Trump. But Clinton has some popular friends. Half the country approves of the job President Obama is doing, and he's seen as more popular than not, on net. In Bloomberg's poll, the four most popular people were all Democrats who will campaign for Clinton: Michelle Obama, Bill Clinton, Chelsea Clinton and Tim Kaine (though fewer people know Kaine or Chelsea). Clinton's popularity is about as bad as the Republican Party's; Trump's favorability is stuck between the Republican Party and Vladimir Putin, which seems somehow meaningful.

On top of all of this, Trump isn't really running a campaign, with no TV ads running and no real effort on the ground. Even if his campaign were operating flawlessly and he weren't distracting everyone by making contentious comments, Trump would have a big hill to climb to appeal to a broader group of people.

But it's not clear he's even trying to climb it.