Hillary Clinton shares a laugh with fellow female lawmakers at a rally in Manchester, N.H., on Feb. 5, 2016. (Melina Mara/The Washington Post)

Hillary Clinton's political career has featured many ups and downs. But the salad days of her popularity were when she was secretary of state. As many as two-thirds of Americans liked her at the time.

Since then, her trajectory has been in one direction: down. And before the Democratic National Convention two weeks ago, her numbers were worse than at any point in her political career.

That was then.

A new Washington Post-ABC News poll is the latest to show Clinton surging to a big lead in the presidential race. And a large reason for that is that Democrats have quickly rallied to her cause. Today, 63 percent of Democrats say they have a "strongly favorable" opinion of Clinton. That number is up a whopping 21 points from less than a month ago, and it's the highest it has been since 2012, when Clinton was a popular secretary of state.

Her overall numbers haven't ticked up that much — the Post-ABC poll shows her favorable/unfavorable split among registered voters at a pedestrian 46/52 — but the rallying effect among Democrats is particularly notable because it hasn't been a given. Just two weeks ago at this time, some Bernie Sanders supporters were trying to throw the Democratic National Convention into disarray, and the narrative was all about a divided Democratic Party.

Clinton's rise among Democrats is also in stark contrast to Republican enthusiasm for Trump. While 63 percent of Democrats say they feel strongly favorable about Clinton, just 36 percent of Republicans have a "strongly favorable" view of their nominee. And the 27-point gap between Democrats who really like Clinton and Republicans who really like Trump suggests a pretty significant enthusiasm gap.

It's worth emphasizing here that the traditional definition of an enthusiasm gap isn't candidate favorability. But we don't have a good recent poll testing just how much both Clinton's and Trump's voters say they're enthusiastic about the 2016 election. And liking you candidate is certainly a big part of it.

Another part of that could be enthusiasm for voting against the other candidate. And for Trump and Clinton backers alike, the other candidate is certainly a very capable and very scary alternative; 82 percent of Republicans strongly dislike Clinton, and 85 percent of Democrats strongly dislike Trump. But having your own partisans excited about your campaign is the kind of thing that feeds grass-roots volunteer support, donations and turnout.

Right now, for the vast majority of Republicans, the 2016 election is about electing Not Hillary Clinton, but for the vast majority of Democrats, it's about electing Hillary Clinton and Not Donald Trump.

That could change again as we get farther from the successful Democratic convention — and Clinton's numbers have certainly been depressed among Democrats before — but for now, it's a development worth paying close attention to.