You wouldn’t know it from watching the cable networks, but what happened yesterday in Nebraska’s Republican Senate primary, where no-name State Senator Deb Fischer defeated state Attorney General Jon Bruning, is a major story, with several nationally important implications. Here are four of the most critical.

1. Start from the beginning: it put a very likely pickup for the GOP in some jeopardy. I would have made Bruning an overwhelming favorite over former Democratic Senator Bob Kerrey. Deb Fischer? Who knows? She certainly starts with a solid advantage, given the partisan tilt of the state, but there’s really no way of knowing yet what kind of candidate she’ll be, what kind of vulnerabilities she has, and how she’ll handle her first-ever statewide campaign.

Remember, she mainly won because outside money destroyed the frontrunner, not because of any particular thing she did or said. She may prove to be a solid campaigner, but we won’t know either way for some time. And don’t forget — this is just one of a series of primaries that, overall, are tilting the Senate playing field towards the Democrats.

2. Even if Fischer ends up losing the general election, this already marks another victory for Jim DeMint, the Club for Growth, and other national conservative and Tea Party groups. They backed Don Stenberg, who finished a poor third. Yet what matters to them most, I’d say, isn’t whether they have hand-picked allies in Congress; it’s that Republican Members of Congress are terrified of them. The defeat of Bruning accomplishes that, even if someone else benefitted.

3. Yesterday’s primary significantly contributes to an emerging problem: expect more recruitment problems for Republicans in the next election cycles. Jon Bruning, the Nebraska Attorney General, was exactly the kind of candidate the national party committees drool over. And yet he was unable to close the deal. More to the point, the sorts of people who want strong general election candidates were unable to do much to help him. Professional politicians watch things like that, and make calculations based on it. Candidates matter in Congressional elections, and on balance this could mean weaker GOP general election candidates in the future.

4. This outcome reveals a key fact about the post-Citizens United landscape. We are going to see a lot more outcomes like this one. Outside money matters more in Congressional races than presidential, and more in primaries than general elections.  That’s not necessarily a bad thing, but for better or worse it’s the world that we live in now. And as we’ve just discovered, a single donor can be responsible for the election of a general election Senate candidate — or even, if Fischer wins, a Senator.

Two, three, or even five years from now, the Senate is likely going to look very different than it does today. Perhaps Democrats will be firmly in control of the Upper Chamber. Or perhaps a far more conservative Republican Party than today’s will dominate it. Everyone will be trying to explain the change. What happened in Nebraska yesterday — along with the defeat of Dick Lugar in Indiana, and other primary elections still to come — are going to be a big part of that explanation.