Scott Brown has turned this town upside down.

Usually, the tendency among political reporters and operatives alike is to overreact and overinterpret elections.

And there are caveats to the stunner in Massachusetts. Yes, this was a special election, which often produces unusual results. Yes, Democrat Martha Coakley ran a timid, sometimes terrible, campaign for Ted Kennedy’s old Senate seat. And it’s true that Massachusetts is not as liberal as many people assumed.

But none of that counters the stunning reality of an election where breathtaking results more than justify breathless analysis. Here’s why:

The lock is broken

There is no way for Democrats to spin an upside to losing their 60th vote in the Senate.

Without it, the health care bill that passed one month ago with 60 votes would go down today. Same goes for any other bill Republicans decide to torpedo with unity, obstruction or whatever one wants to call zero votes.

There are ways Democrats can jam through the current health care bill with procedural tricks or legislative creativity. But what seemed a certainty a week ago feels unlikely today. Don't take the word of Republicans or even reporters on this one. Listen to what Democrats are saying as they appraised the results overnight:

Sen. Russ Feingold (D-Wis.) told a local reporter, “It’s probably back to the drawing board on health care, which is unfortunate.” Rep. Bill Delahunt (D-Mass.) told MSNBC this morning he will advise Democratic leaders to scrap the big bill and move small, more popular pieces that can attract Republicans. And Anthony Weiner (D-N.Y.) said his leadership is “whistling past the graveyard” if they think Brown’s win won’t force a rethinking of the health care plan.

Sen. Evan Bayh (D-Ind.), who now might draw a challenge from Rep. Mike Pence (R-Ind.), said the party needs to rethink its entire approach to governing.

The fear is unleashed

Any Democrat with even the faintest fear of a tough race in 2010 is rattled. It was easy for some to rationalize the defeats in New Jersey and Virginia last year — and even the flood of polls showing bad news since then.

They are in denial no more: If Democrats can lose in Massachusetts, they can lose anywhere. That is the mind-set that will shape the next nine months for Democrats. It will affect who runs for reelection, who bolts on big votes, who gives money and who speaks out against Obama. All of this will make governing harder.

The focus has been on the special election for the past week. But Democratic insiders were equally concerned about other signs of trouble that got insufficient notice: Polls show Democrats could lose the New York Senate seat, Democratic Sen. Ben Nelson’s favorable ratings plummeted in Nebraska, new polls showed Rep. Steve Driehaus (D-Ohio) trailing badly in his swing district, and Rep. Tim Bishop (D-N.Y.) is in a statistical tie and in more trouble than previously expected.

Again, it's the appraisal of Democratic lawmakers overnight that speaks loudest. Rep. Jason Altmire (D-Pa.) told us the results prove that unhappiness with political leaders has “gone mainstream” and could hit anyone. Rep. Allen Boyd (D-Fla.) said “when it happens in Massachusetts, it really throws us a curve. It’s a big deal for a lot of members here.”

The leaders are rattled 

It has been an ugly 24 hours of blame-casting for Democrats. In fact, it's the first time in the Obama era that so many Democrats aired their private grievances in such a public way.

The White House blamed Martha Coakley’s campaign. Speaker Nancy Pelosi seemed to fault Senate Democrats. Senate Democrats, in turn, put the blame back on Coakley, who had campaign officials thrashing the White House and Senate leaders by mid-day Tuesday — hours before the polls closed.

Chalk this up to frayed nerves. But the Democratic unity that brought health care to the brink of passage will be tested like never before in coming days. Democrats on Capitol Hill told us they could be headed for a major clash with Obama. The reason: Obama’s agenda — getting health care to prove he can govern and earn reelection — could quickly be in tension with lawmakers' agenda of saving their jobs.

David Axelrod told POLITICO it would be a “terrible mistake to walk away now” and “leave the stigma of a caricature” of a failed bill and effort. Pelosi and Harry Reid agree — but many members are demanding they think again. Rep. Carolyn Maloney, speaking to the New York Daily News as results were coming in last night, put it bluntly: “If she loses, it’s over.”

By contrast, David Plouffe, who ran the Obama campaign in '08, said in an interview it's imperative Democrats not back down, calling it a "test of our party and whether we truly are ready to lead."

The angry independent wins

Ideologues and hard-core partisans dominate the leadership of both parties and the cable TV debates. But it’s the independents who are the deciders in most elections.

This voting bloc has swung decisively against Democrats, starting this past summer. A review of polling in Massachusetts, in other states and nationally shows the same thing: By about a 2-to-1 margin, independents have turned on Democrats.

A new Wall Street Journal/NBC News poll found that two-thirds of independents would prefer Republicans controlled Congress. The same polls show the voters don’t even like Republicans. A CBS News poll showed only one-third of independents approve of Obama’s handling of the economy — a nearly 20-point drop in less than one year.

In all three big Democratic losses this past year — in New Jersey, Virginia and now Massachusetts — better than 60 percent of independents said they backed Republicans.

It would be a mistake for Republicans and Democrats to chalk this up to the health care bill. Independents consistently tell pollsters they aren’t happy with anything Washington is doing when it comes to the economy and domestic issues.

For the foreseeable future, the wrath of independents will hit Democrats hardest.

Grand Old Possibility

Democrats are right that polls show the vast majority of the public holds Republicans in even lower esteem. But that might not matter because they blew the last two elections — and no longer own what Washington does.

House Minority Whip Eric Cantor (R-Va.) and others are bragging that they have a real shot at winning back the House. They would need to net 40 seats to do so.

Republicans say they have recruited some quality candidates in winnable seats. Democrats grudgingly agree. But Republicans are getting their clocks cleaned when it comes to fundraising, especially by the House campaign committees. Democrats gleefully agree.

The special election — and the enthusiasm it has generated among conservatives — will make it a lot easier for the GOP to raise money and recruit volunteers. It gives conservatives, many of whom remain frustrated by memories of free-spending Republicans when they controlled things, now have a cause. The NRCC blasted out a fundraising appeal overnight — and plans to leverage the results to convince candidates to run in races once seen as unwinnable. GOP fundraisers say the special election — combined with Obama’s new attacks on Wall Street — has some big companies hedging their bets by investing more in the minority.

Cantor told us earlier this month that Republicans will spend most of their money and energy running negative campaigns. It’s a convenient way of glossing over the party’s own weaknesses — and Brown proved this can be effective.

The Obama magic has vanished

Think back a year ago and imagine someone saying Obama would throw his support behind Democrats in New Jersey, Virginia and Ted Kennedy's Massachusetts — and lose all of them.

Think back a year ago and imagine someone saying he would celebrate his first anniversary without having gotten health care, financial regulation or energy legislation signed into law. And that less than 50 percent of the public would hold a favorable view of his presidency.

Obama clearly remains popular at the personal level, a big asset that Republicans privately concede could easily help turn things around for this White House in the months ahead. But it is similarly clear that the Obama magic of 2008 has vanished. His personal popularity is plainly not transferable to other Democrats. His power with Democrats is somewhat diminished.

So much now rides on health care for Obama. His top advisers have told reporters for months that he will be judged on one issue and one issue alone: getting health care signed into law. They now realize the bill — and, with it, Obama’s reputation and leverage on Capitol Hill — could go down. As they look ahead to the rest of the year, White House advisers talk publicly of bold action, but most of the talk in private is smaller, less controversial action. Deficits. Incremental changes to energy policy. Debt commissions.

This is not the way Obama — or many of the people watching him at his inaugural address a year ago — expected that he would mark his first anniversary.