It's been a busy week for Hillary Clinton, that's for sure. But while almost all of the media attention has been on the results of the F.B.I.'s investigation into her email server, Clinton also took the biggest step she's yet taken to offer the supporters of Bernie Sanders an inspiring reason to vote for her. Her embrace of the "tuition-free college" idea Bernie ran on is a fundamental shift in direction for Clinton's campaign, and represents the biggest effort she's so far made to woo his voters into her camp. Sanders is rumored to be on the brink of formally endorsing Clinton (which could happen early next week, perhaps in New Hampshire), so her college tuition shift could be his last big influence on her agenda.

Sanders has not, of course, suspended his campaign as of yet. He's been hanging in there as a thorn in Clinton's side in an effort to dramatically change the direction of the Democratic Party. So far, he's been impressively successful in doing so. He has won many concessions on the party's platform document. Sanders didn't get everything he wanted, but he got enough items into the document to show the importance of the campaign agenda he ran on to millions of Democratic voters. Bernie has shaken the party loose from their timidity and complacency on a number of issues, and he also showed Democrats what a positive agenda for change can accomplish with the electorate. By writing many of the planks of the platform, he ensures that Democrats will be still paying attention to these issues long after the election is over. He has moved much of his agenda from being described as "fringe" or "radical" into being mainstream Democratic ideas. That's an impressive accomplishment by any measure.

But up until now, while Bernie Sanders has been working the platform committee as hard as possible, Hillary Clinton herself hasn't shifted her positions much. Her natural inclination at this point (as would be true for any politician in her position, to be fair) is to "tack to the center" for the general election. In other words, soften some of the bolder stances she's so far taken and hedge some of the language she previously used. This is basic presidential politics, designed to appeal to the center and all the undecided voters who usually swing entire elections.

But this is anything but a textbook presidential election, to put it mildly. At the moment, it looks like it could shape up into an election where most voters are voting against the other guy (or gal). Both Hillary Clinton and Donald Trump have historically-high negative ratings in polls. Clinton would benefit from a higher level of enthusiasm from her own base, to put this another way. Which is why the college tuition move could be an important one.

It's pretty obvious why this particular issue is the one Clinton chose to make a big move on. The demographics almost demanded it. Bernie enjoyed overwhelming support among younger Democratic voters in the primaries. These younger voters are not all that impressed with Hillary Clinton, since most of them don't even remember when her husband was president. Her history and her previous accomplishments don't move the youth vote much at all. So what is one of the biggest issues for this demographic? College debt. The high price of higher education. Spending your 20s (and 30s, sometimes) paying off massive piles of debt rather than buying new cars or your first house. This is an issue which touches millions of families and so far Clinton's ideas to make the situation better have been pretty small-bore.

During the primaries, she touted her own plan, which would have required the students to (as she put it) "have some skin in the game" -- meaning having to work while going to college, for the most part. Students who already have plenty of skin in the game of getting a college degree weren't all that impressed, to put it mildly. Hillary denounced Bernie's "tuition-free state college for all" plan as being too expensive, too unreasonable, and "paying for Donald Trump's kids to go to college." Not very inspiring stuff, for young voters. How many rich people's kids go to state schools rather than private colleges, after all?

Clinton began timidly moving on the issue last week. Her first two ideas were, once again, so incremental as to be little actual help to students awash in debt: a three-month extension of the window students have after they graduate before they have to start paying off their student loans, and forgiving student loans for entrepreneurs who start a successful business and employ others. Three extra months is nice, but doesn't change much of anything in the long run. And if you're going to be the next Bill Gates or Steve Jobs, it's likely you won't be all that worried about paying off your student debts in the first place. Starting a business sounds nice and all, but usually requires tens of thousands of dollars to get off the ground, and few students have access to that kind of borrowing ability with all those student loans hanging over their heads (unless their parents help pay for it). None of Clinton's proposals would make any sort of fundamental change in the system, which was (coincidentally) the biggest reason young Bernie supporters haven't been on Hillary's side all along. Incrementalism isn't very inspiring, in other words.

This is why Clinton's movement on student debt is a big one. She still couldn't quite bring herself to adopt Bernie's simple position ("tuition-free state college and university for all"), but she got pretty close to it, offering tuition-free state college and university for the poor and most of the middle class. Families making under $125,000 (this limit would actually start at $85,000 and move up to $125,000 in a few years) will all be eligible, which is not "for all" but does cover a big enough chunk of the families worried about paying college bills as to qualify as a big and fundamental change. Clinton is clearly trying to woo Bernie supporters with this move. Much more important than some language changes in the party platform, this is an issue which Bernie could actually campaign on for Clinton. That's a fairly big deal, because so far it's the biggest shift he's convinced her to make, at least since the primaries were over.

Tuition-free college isn't the same as "free college." It doesn't cover books, supplies, housing, or food. College students may still have to take out loans or work to get an education, in other words. But it'll lessen the cost enormously for millions, and for plenty of families out there it might mean the difference between being able to afford an education or giving up all hopes of going to college.

Conventional wisdom and polling were already indicating that Hillary Clinton wouldn't have as big a problem unifying the Democratic Party as some would have predicted. Since the primaries ended, a much larger percent of the Democratic base have already moved over to her side (rather than stating they'd vote for the Republican candidate) than was true in 2008. The rift between Clinton supporters and Obama supporters was actually a lot bigger back then, and it healed a lot more slowly. But then again, back then there was a Republican candidate Democrats could see as being plausibly presidential, which is not exactly the case this time around.

The safe choice for Hillary would have been to just ignore Bernie, let him have his way with the platform document, and then make the inevitable tack to the center. The polling backed up this choice, and she could have just tried to use the fear of President Trump to turn former Bernie voters out in November. Instead, she has chosen a big issue for the largest demographic of Bernie voters out there, and staked out a position almost as bold as that taken by Sanders himself. By doing so, she may have finally convinced Bernie to offer her his full-throated support. Bernie can tell his own supporters to get behind Clinton, since he successfully convinced her to take such a big step towards tuition-free college. Of course, he's not going to convince everyone who supported him to back Clinton (some will stay home in disillusionment, some will vote for Jill Stein), but he's now got a solid reason why electing Clinton could truly improve the lives of his youthful supporters. He can claim -- rightly so -- that he was the sole reason for her shift in position, and that he stayed in the race long enough to make it happen. It's impossible to say how much this argument will resonate with his young supporters, but it's a lot better argument than just "Trump would be a disaster." It might just be enough to give a lot of young voters a big reason to vote for Hillary, not just against the other guy, in other words.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant