Rupert Cornwell: Heads roll as voters play 'kick the incumbent'

Out of America: Politicians who've been secure for decades are feeling extremely vulnerable as mid-term primaries point them to the exit

On Capitol Hill positions on the Middle East are often more rigid than even those of the Netanyahu government (Reuters)

Whoever paid much attention before to Congressional primaries? Britain traditionally votes on Thursdays. In America it's Tuesdays, as anyone who follows US presidential politics knows well. But Tuesdays in April, May and June in a non-Presidential year? Well, this year people are paying attention. Because this primary season ahead of November's mid-term elections for the Senate and the House of Representatives are transforming the country's political landscape.

The Tea Party has, of course, made the biggest headlines as it sends shockwaves through the Republican establishment. After backing Scott Brown in his sensational victory in Massachusetts in January that cost the Democrats their filibuster-proof majority in the Senate, the movement has forced Charlie Crist, the popular governor of Florida, to pull out of the primary to select the Republican candidate for that state's vacant Senate seat.

Earlier this month, Tea Party activists gained their biggest scalp by toppling Bob Bennett, for the past 18 years Republican Senator for Utah, not just the most Republican state in the Union but also the land of the Mormons, famed for their respect for elders. They could claim another one this Tuesday in Kentucky's Senate primary, if the Tea Party-backed candidate prevails over the establishment figure supported by Mitch McConnell, the state's senior senator and, as minority leader in the Senate, the country's top-ranking Republican.

The anti-incumbent tide though is not just washing away Republican grandees. A Washington Post poll the other day found that only 30 per cent of voters plan to support their sitting senator or member of Congress this autumn, an insurgency unmatched since 1994, when Republicans captured the House for the first time in 40 years. Now, as then, Democrats control Capitol Hill, so simple arithmetic makes them more vulnerable than their rivals.

As a result, half a dozen Democratic House committee chairmen, among the most powerful individuals in Congress, have already run for the exits, announcing that they won't stand again in November. But in some cases, they're not even being given the chance.

Last Tuesday, Alan Mollohan, who has represented a rock-solid Democratic district in West Virginia for the past 28 years, was given his marching orders by primary voters in West Virginia, a state not usually associated with dramatic political gestures. Mollohan became the first Democratic incumbent to be deselected in 2010, and almost certainly won't be the last.

This Tuesday, a couple of sitting senators face the primary music. In Pennsylvania, Arlen Specter, who last year briefly became the filibuster-beating 60th Democratic vote when he defected from the Republicans, could well be beaten; so too could Blanche Lincoln in Arkansas. This last contest is a mirror image of the Tea Party challenges from the right against sitting Republicans. Lincoln is a moderate, and her opponent is from the left. But she's in trouble for exactly the same reason that Bennett was in Utah: a voter backlash against Washington and all its works.

And in the general election yet worse could await the party. By common consent, the Republicans now have a shot at repeating their 1994 feat. Take once reliably Democratic Massachusetts, where Scott Brown first upset the applecart in January. All 10 of the state's seats in the House are currently (and comfortably) held by Democrats. Now Republicans are queuing up to challenge them. In 2008 Niki Tsongas, widow of Paul Tsongas the former senator and presidential hopeful, did not even have a Republican opponent. This year a dozen are seeking the right to take her on.

And yet worse could follow. If Massachusetts wavers, where in the US is safe for Democrats? Certainly not Nevada, where polls say Harry Reid – Senate majority leader and the third most powerful Democrat in the land after Speaker Nancy Pelosi and President Obama himself – is heading for defeat in November. If Reid goes, so too could Democrat control of the Senate, something unimaginable on that magical November night, only 18 months ago, when Obama came to power.

Even now it's hard to make sense of the present upheavals. Not only the Tea Party on the right but – far more important, independents in the centre who decide elections – are up in arms at that familiar American bogeyman, "Big Government". They worry deeply about the deficit and are wary of healthcare reform. Yet was government activism ever more needed, than when recession threatened to turn into depression, and 50 million people without health coverage could be overtaken at any moment by financial ruin?

There are other factors too. Notably there is the poisonously partisan atmosphere on Capitol Hill, the impression given of endless petty feuding (even though this Congress has been one of the most productive in recent memory). In that sense too, a "throw the bums out" mood is understandable. But somehow it still doesn't add up.

So maybe something else is in play – the eternal tension between individual states and the centre. Maybe the balance has tilted too far towards the centre. Maybe these primary revolts are the states' revenge against their entrenched and arrogant masters in Washington DC. If so, the next instalment of the rebellion comes on Tuesday.