One short month ago, millennial voters were severely complicating Hillary Clinton's path to the presidency. This liberal-leaning but highly nonpartisan demographic didn't like Clinton and was flirting heavily with going third-party. Her lead among them was negligible — only two points in one poll. It was a big liability.

That was a month ago.

Today, in fact, Clinton looks like she might even outperform President Obama among young voters. And it's a big reason she's grabbed a lead in the polls.

A new poll of 18-to-29-year olds from the Harvard Institute of Politics shows Clinton leading Donald Trump by 28 points among young likely voters in a four-way matchup that includes Gary Johnson and Jill Stein, 49 percent to 21 percent. That 28-point margin is notably bigger than Obama's 23-point margin in 2012, when he beat Mitt Romney 60-37 among this group.

And there's evidence that Clinton's lead could grow from there. Libertarian Gary Johnson takes 13 percent of likely voters, and Green Party nominee Jill Stein takes 6 percent — both down from where they were previously. And it's likely they'll drop further as young voters confront a choice between a protest vote and picking between Clinton and Trump (third-party candidates almost always see their vote share drop off at the end. That's happening to Johnson right now).

Tellingly, fully 37 percent of Johnson supporters admit that it's “likely” they'll vote for someone else.

That would very likely accrue to Clinton's benefit. Harvard also tested a straight head-to-head between her and Trump. Her support rose from 49 percent to 59 percent, while Trump's went from 21 percent to 25 percent. So it stands to reason that Clinton could exceed even that 28-point margin on Election Day.

What's more, these data basically confirm what we've seen in other polling. Earlier this week, a GenForward survey conducted by the AP-NORC Center for Public Affairs Research showed Clinton leading among voters 18 to 30 by an even bigger 60-19 margin, with Johnson at 12 percent.

Just as a refresher, polls last month showed Clinton leading among young people by just 2 pointsby 5 points, by 9 points and even trailing in the unorthodox and Trump-friendly USC Dornsife/Los Angeles Times poll.

Clinton's margins are now between 28 and 41 points in these new polls, while Obama won them by 23 points in 2012 and 34 points in 2008.

Of course, this isn't because Clinton is suddenly beloved by young people. She has clearly made herself an acceptable choice, but the fact that she could take as much as 6 in 10 votes from them probably has more to do with Trump than with Clinton.

The Harvard poll shows her favorable rating among all 18- to 29-year-olds is 40 percent, up from 31 percent in July and 37 percent in April. But on top of that slightly improved image, the universe of likely voters is significantly better for Clinton — with 48 percent having a favorable opinion of her.

Trump's numbers, meanwhile, have remained horrible. Fully 76 percent of likely young voters don't like him; just 22 percent do.

With numbers like that, it was always far-fetched that Trump would match Mitt Romney's 37 percent showing among this group. His best hope was that Johnson and/or Stein would continue to win over young voters who don't have much affection for Clinton, and that this would eat into her margin.

Instead, the rallying effect to Clinton among young voters appears to be one of the big stories of the closing weeks of the 2016 election.