With the Democrats’ post-convention bump settling into a nice two-to-three point lead in the presidential race — and the near campaign-ending gaffe from Mitt Romney yesterday — Team Obama is starting to breathe a little easier. But even if holding the White House seems more certain, the fight for Obama is much bigger.

Republicans, at the height of their hubris, thought they might regain in the Senate in this cycle — thus giving them the potential of a clean sweep of both arms of elected government, allowing them to make sweeping changes to American politics and society. That hope is also fading, though the upper house remains on a knife edge.

Currently the Democrats enjoy a 53-47 edge in the 100-seat chamber, although two of those 53 are independents — Bernie Sanders of Vermont, a self-described socialist and, less dependable, Joe Lieberman of Connecticut, a former Democrat (and indeed the party’s 2000 vice-presidential candidate), dumped by the Democrats for hawkishness and gaining re-election in his own right.

Of course, in a more exact sense, no one has control of the Senate. A straight majority allows a party to get a budget through and resist impeachment votes, among other measures, but for the past decade or so the Senate has become dominated by the “filibuster” vote — whereby votes on substantive measures are preceded by procedural votes that require a super-majority of 60 votes. Without those, the substantive bill can be left on the table. The Democrats had super-majority control of the Senate for only two months, following the 2008 election — actually in 2009, when Minnesota Senator Al Franken was seated after a long-disputed result, and before the late Ted Kennedy’s Massachusetts seat was, unbelievably, lost to Republican Scott Brown.

Of the 33 seats up for grabs (a third of the Senate is re-elected every two years) only about 10 are truly in play, the majority of them Democrat. Most pundits believe that the Nebraska seat currently held by the Democrats is toast — for the past 12 years, it’s been held by Ben Nelson, one of the last of the dwindling band of “Blue Dog” Democrats. Largely elected in areas that have moved rightwards over the past decade or so, the Blue Dogs attempted to hold on to their seats by voting against nearly every measure the Democratic leadership put forward, save for the biggest, such as Obamacare. But since the election of Obama, even these desperate measures — and a huge amount of pork poured their way — has failed to hold their position. In 2010, most of the 40 or so Blue Dogs were driven out of the house; now they are beginning to be pushed out of the Senate.

Another right-wing Democrat seat for which the Republicans had high hopes was Missouri — a one-time bellwether state, swinging reliably with the governing party. But the state has moved rightward and Democratic incumbent Claire McCaskill was seen to be on the ropes, against a GOP contender named … Todd Akin, he of the now notorious “women have a way of shutting that thing down” comments regarding “legitimate” r-pe. Before those comments, Akin was leading McCaskill by 5-10 points; it’s a measure of how right-shifted the Mid-West is, that he’s still running evens with McCaskill, despite calls by the Republican Party and Mitt Romney for him to get out of the race. The party turned off his money supply, but Akin has managed to reboot with local, and even further right-shifted donors.

The other two seats the Republicans are likely to take from the Democrats are North Dakota and Wisconsin. In North Dakota, Kent Conrad has been holding the seat since 1988, and was re-elected in 2006 with 70% of the vote. Despite that, the state will most likely go to the Republicans — another example of voters being loyal to a cross-party incumbent, and reverting when they retire.

Conrad’s career has been a shining example of the manoeuvres a Democrat has to make, to stay electable in a state that was once a bastion of mainline protestantism, and is fast becoming one of the most evangelical states in the nation. Voting against the Iraq war, but for the Patriot Act, against late-term abortion, but for legalisation of abortion in the military (US servicewomen currently cannot get abortions), in favour of a balanced budget but also for farm subsidies. Overall, he has succeeded in recent years because he has been identified with the shale oil boom that is currently transforming the state.

Conrad’s retirement has immediately lost the Democrats the 20% vote margin they enjoyed — and perhaps more. The GOP candidate is a hard-right congressman named Rick Berg, who has achieved fame of a sort for proposing that abortion not only be criminalised, but be made an AA-class felony, equivalent to murder. It’s this sort of thing that has given his opponent, Heidi Heitkamp, a fighting chance. Though she is hardly of the left — she opposes most of Obamacare, and is enthusiastically pro-drilling — she has been constructed as an ultra-liberal by the state’s compliant press, perhaps for having short hair and wearing slacks. But if she can hold off Berg’s challenge — the state has become an ad-buy battleground, with nearly $20 million expected to come in by election day — then the Republicans’ dream of a Senate takeover will be in deep trouble.

Wisconsin, their other fond hope, exemplifies the cultural bias towards incumbency to an even greater degree. Retiring Democratic Senator Herb Kohl is an old-fashioned liberal, on all main issues — healthcare, guns, abortion, affirmative action — save a few fiscal issues. He won the seat with 52% of the vote in 1988 — and with 70% in 2006. Despite that the state, once the centre of US progressivism, was slipping rightwards. In 2010, the state sacked veteran Senator Russ Feingold, one of the few genuine leftists in Congress (and also a bipartisan Senator, being the other half of the now superseded McCain-Feingold Act) and replaced him with Ron Johnson, a Tea Party-favoured lunatic.

The progressives are still there in Wisconsin — it’s just that they’re contested by a now extremist and hitherto centrist Right. Matters came to a head with an attempt by a movement of unions and social groups to recall governor Scott Walker, who had attempted to remove union rights from public workers. The recall move failed, and the effort stirred up the Right to greater effort. Their efforts are redoubled by the fact that the Republican candidate — former Bush cabinet health secretary Tommy Thompson, college football star, ex-military, y’get it, is running against Tammy Baldwin, one of the few out lesbian congresswomen. Though her positions are the same as Kohl’s on most issues, she will not get anything like his vote.

The Republicans are also targeting Virginia, where Democratic red-haired wunderkind Jim Webb, turned out to be a one-term Senator for reasons not yet fully explained. George Allen, a former Senator from Virginia, is running — predictably enough as an outsider — while the Democrats are putting up former governor Tim Kaine, thus making it about as insider’s an election you can get. The lead has been changing every fortnight, and it’s not one the Republicans can rely on.

Beyond that, the Democrats have to hold the line on a range of seats — New Jersey, Michigan, West Virginia, Pennsylvania, Florida, Ohio — but most of these, once thought to be in play, are now supposed to return to the blue side of the aisle. Furthermore, they also have a chance to pick up several Republican seats. Their best bet is via someone who isn’t a Democrat at all — Angus King, a former independent governor of Maine, who has announced that he will run for the seat vacated by moderate Republican Olympia Snowe. Snowe quit, chiding the “hyper-partisan” atmosphere of the chamber — but the comment was largely directed at the right-shifted leadership of her party. Her vote was phenomenal, in a state that reliably votes for Democratic presidents, but has two republican senators — in 2006, Snowe received 73% of the vote.

King has been running at around 45-50%, with the Republicans at 23%, and Democrats at 7% (though they are running dead). King has not said which party he will caucus with — if either, but he is far more likely to cleave to the Democratic Party than the GOP’s Jesus-freak Ayn Rand r-pey circus. Another anomalous election is the Massachusetts race, where Scott Brown — the truck-driving one-time male centrefold — took the late Ted Kennedy’s seat after the laziest most lacklustre self-satisfied campaign from the Democrats.

The contender is Elizabeth Warren, a hero on the wonkish left-liberal side for fighting to establish a credit regulation act, to stop the selling of shonky mortgages, credit card sharking, etc. Democrats assumed that the race would be a simple restoration of the natural order. But Warren is no local and Brown is Boston down to his red sox, has voted with the Democrats on numerous occasions. Brown’s personable, Warren’s a little snotty, and if Bostonians want snotty, well they’ve got MIT and Harvard down the road, they don’t need more of it. The race may close up, but at this point it looks as if the Democrats’ unique ability to really screw up the basics will see Kennedy’s seat become an embedded Republican one.

Other possibilities for the Democrats include Nevada — where Republican John Ensign became the latest “values politician” to confess to an affair, and resign the seat, putting it into play. In Indiana, Richard Lugar, one of the most respected bipartisan Senate bill-wranglers fell victim to a Tea Party attack in the primaries. Lugar was so popular, and so useful to the Democrats that they hadn’t even run against him in 2006 — a move that helped damn him. Richard Mourdock, who objects to the entire US welfare apparatus because it is not specifically enumerated in the constitution, opposes abortion save for “crisis pregnancies” (see Ensign above), yadayadya, and consequently is running behind the Democratic candidate by around 5% — in the one state that Obama is certain to lose back to the Republicans.

So what’s the most likely result? It may well be one of those distinctive American things, a seat swap that leaves the party positions much as before. The Dems will lose Nebraska, North Dakota and Wisconsin, they’ll gain Maine, Indiana and Nevada, and the balance will remain (although the composition will be three independents not two, among the 53 Democratic caucus) — with one or two either way. If the Republicans can drag one or two more of the half-dozen or so marginal Democratic seats across the line — which should not be impossible — then they may get their Senate after all.

Which means that the likely defeat of Mitt Romney must be driving them krraaaaaazzyyy …