Supreme Court could decide second US election in a row

America's mid-term elections are just four weeks away, and any doubt they will be cliffhangers vanished last week with the re-appearance in the fray of that ghost of elections past – the United States Supreme Court.

Two years ago, the highest court in the land cast the final and decisive vote in the battle between George Bush and Al Gore for the White House. This time the Republicans are begging it to overturn a New Jersey Supreme Court ruling allowing the Democrats to change their candidate, less than a month before voting day on 5 November.

Normally, the replacement of the ambitious and much disliked Robert Torricelli with the likeable old warhorse Frank Lautenberg would be a cause for much rejoicing. But not among Republicans. The scandal-tainted Mr Torricelli was heading for certain defeat, and that one seat might just have been enough to return the Senate to Republican control.

The real lesson of the no-holds-barred legal fight over New Jersey – just as the one over Florida – reflects the basic truth about US politics that no Supreme Court ruling can modify: the two major parties are utterly deadlocked, and every single vote matters.

The stalemate was evident in the closest presidential election in over a century. It is evident in the current make-up of the Senate, tied 50-50 until the Vermont Republican, James Jefford, became an independent, voting with the Democrats. It is evident in the House, where the Democrats need to win a net six of the 435 seats at stake to gain control.

Right now, the Republicans have the edge, if only because of Mr Bush's sustained popularity and record-shattering fundraising – $132m (£85m) so far this season – and because the Iraq crisis, playing to the Republicans' strength on national security issues, has driven all else off the political radar screen. In the tiny number of races – perhaps 30 out of 435 for the House and 12 or so in the Senate – that are genuinely competitive, it is Democrats who are sweating most.

The replacement of Mr Torricelli by Mr Lautenberg (Supreme Court permitting) may just be enough to save New Jersey for the Democrats. The state, after all, hasn't sent a Republican to the US Senate in 30 years.

But in at least three Mid-Western states, incumbent Democrats have tough fights. In Minnesota Paul Wellstone, the most liberal member of the Senate, has made a difficult race even harder with his scepticism towards administration policy on Iraq. Jean Carnahan, elected in place of her husband who was killed three weeks before the 2000 vote, is trailing slightly in Missouri.

In South Dakota, the Republicans are making a massive effort to topple Tim Johnston, whose campaign in a basically Republican state has also suffered from all-consuming Iraq. A Johnston defeat would doubly delight the Republicans as a kick in the face for the state's other Senator, the majority leader Tom Daschle, whom the White House loathes.

The Democrats are hoping to make gains in Arkansas, Colorado, and perhaps in the Texas seat being vacated by Phil Gramm. But Elizabeth Dole looks set to bring the Dole family back into the Senate from North Carolina, as successor to the cussed old conservative Jesse Helms. Everywhere, much depends on whether the Democrats can switch the argument from Iraq to the issues that ought to favour them – from soaring healthcare costs to the rickety economy and corporate misbehaviour.

Finally there is the small matter of 36 governors' elections. They include the four most populous states: California (probably safe for the Democrats), Texas, New York (probably safe for the Republicans) – and, yes, Florida.

Mr Bush could live with losing both the Senate and the House (after all Presidents Reagan, Bush senior and Clinton had to contend with Congress in the hands of the other party). Whether he could survive his brother Jeb losing to Bill McBride in Florida is another matter.

Without Jeb Bush's state Republican machine, brother George would not have carried the state, and Florida will be crucial in 2004 as well. Mr McBride is exactly the sort of folksy, conservative Democrat who does well in Florida. At present, Mr Bush leads by a shrinking, single-digit margin, and the man in the White House is praying it stays that way.