It’s been a tough couple of weeks for Donald Trump, and the new WBUR/MassINC poll of New Hampshire brings that home — almost literally. In the last iteration in this series in early May, Hillary Clinton had a two-point edge over Trump, 44/42. Since then, Hillary has picked up three points … while Trump has lost ten:

According to a new WBUR poll of New Hampshire voters, Hillary Clinton is enjoying a dramatic post-convention bump and now leads Donald Trump by 15 points. Our poll also shows Democrat Maggie Hassan with a big advantage in her bid to unseat Republican Sen. Kelly Ayotte.

The last time we polled in New Hampshire, three months ago, the presidential contest was virtually tied. Our new poll (topline, crosstabs) of 609 likely New Hampshire voters, conducted July 29 through August 1, shows Clinton leading Trump 47 percent to 32 percent. When Libertarian Gary Johnson and Green Party candidate Jill Stein are omitted, Clinton’s 15 point lead swells to 17 points [51/34 – Ed].

MassINC’s president chalks this up to Democratic unity:

“After all the hand-wringing about whether Bernie Sanders supporters would end up supporting Hillary Clinton, she’s now getting 86 percent of the Democratic vote,” explained Steve Koczela, president of MassInc Polling, which conducted the WBUR survey. “Donald Trump, on the other hand, has slipped a bit among Republicans. He’s now getting a bit less than two-thirds of the Republican vote.”

That doesn’t explain the topline results very well, though. Democratic unity might explain going from 44% to 47%, but that could also just be a margin-of-error difference in the status quo. It doesn’t explain why Trump took a ten-point fall in three months. It’s not as if Bernie Bros were forming ten points of Trump’s support in New Hampshire in May.

The conventions — and likely the post-conventions mess on Team Trump — seem much more likely explanations. The survey period went from the day after the Democratic convention through Monday, August 1st. That might get a little too much afterglow for Hillary, but it also managed to be right when Trump mired himself in the fight against Khizr and Ghazala Khan.

Certainly, convention performance contributed to the shift. Fifty-six percent of respondents thought Hillary came out of Philly stronger, while only 39% thought Trump picked up strength coming out of Cleveland. (Almost the same percentage watched them — 68% for the GOP, 71% for Democrats.) Accordingly, Hillary has righted the ship on favorability in New Hampshire, going from 35/58 in May to 45/45 now — not great, but no longer disastrous.

That’s a big problem for a Republican argument that Hillary’s worse than the alternative, especially because the alternative now polls slightly worse on favorables since May’s 33/58. Trump’s now at 29/60. The “lesser of two evils” argument isn’t going to work well in New Hampshire, not unless Hillary craters again on favorables. And even if Hillary’s mild bump upward turns out to be a temporary effect of the convention, that doesn’t help solve Trump’s ten-point drop.

The demos don’t look encouraging, either. Hillary has a 31-point lead among women (58/27) and a four-point lead among men (45/41). Independents — the key to New Hampshire — break by thirty-two points to Hillary, 56/24. In the May WBUR poll, Trump led among men 53/36 and only trailed among independents 41/42. At least in this series, Trump has suffered a collapse much more than Hillary has benefited from unity with the Bernie Brigades.

Is this an outlier? It’s tough to say, as WBUR is first out of the gate in the Granite State with a poll after the conventions. Trump has never led in New Hampshire in any poll aggregated at RealClearPolitics, but Hillary’s lead had been almost entirely in single digits, right up through July 18’s WMUR/UNH poll, which put Hillary up two. If the convention is the inflection point, though, it’s possible we’ll see more polls coming out of New Hampshire like this. At the very least, the dramatic change within the WBUR series should have Republicans very worried about Trump’s prospects in November.