Barack Obama should be losing the 2012 presidential election – or so says the conventional wisdom. With unemployment above 8%, a recovery that is mediocre at best and economic uncertainty far more the rule than the exception, there is certainly something to this argument. Yet, according to polling guru Nate Silver, President Obama is currently a 76% favorite for re-election.

So why does Obama continue to maintain a small, yet stubborn lead not only in general election polling, but – more importantly – in a majority of key swing states? It's the same reason he should be losing the presidential race: his Republican opponents.

That might seem like a confusing explanation, but it's emblematic of the extent to which the GOP has been Obama's worst enemy over the past four years while, at the same time, may ensure that he is re-elected president.

To unpack this admittedly convoluted argument, let's begin with focusing on the dominant political dynamic of the past four years. It's not about President Obama's legislative agenda or his post-partisan dreams, but rather the unceasing and unprecedented obstructionism of the Republican party. From day one of his presidency (actually, even before Obama took office), Republicans made the conscious decision to not just simply oppose Obama's entire policy agenda, but to actively and flagrantly thwart it. They promiscuously used the filibuster to block even the holding of votes on Democratic proposals in the Senate and punished party members who contemplated the idea of working together with Obama or – even worse – compromising with him.

Indeed, that Obama was even able to pass an $800bn stimulus measure and comprehensive healthcare reform is perhaps the single most surprising political story, not just of the past four years, but indeed the past 40.

The Republicans' obstructionist "successes" have taken a heavy toll and can be seen most dramatically in US economic performance since 2009. When fiscal policy has been expansive – as in the case of the stimulus being passed only a few weeks after Obama took office – the result has been job creation and economic growth (albeit of the more tepid variety). When Congress has adopted GOP-favored policies of austerity – spending cuts and reliance on tax cuts to stimulate the economy – the results have been far worse. By consistently opposing and blocking any effort by Obama and the Democrats to grow the economy through additional stimulus measures, like the president's job bill, and even seeking to intimidate the Federal Reserve into focusing its attention on inflation rather than unemployment, they have actively undermined policies with the potential to spark an economic turnaround.

While one can debate the morality of such an approach, the political results speak for themselves. An underperforming economy has harmed the president's political prospects and made him far more vulnerable to defeat than he would have been if Republicans had supported or, at least, not completely obstructed his stimulus efforts. This creates a rather disturbing political dynamic: namely, that the GOP strategy of obstructing Obama's agenda was political savvy and their only real hope of ensuring his defeat in 2012.

Opposition was the only real alternative for a party intent on taking back the White House in four years, and it certainly helped Republicans to take back the house in 2010.

Had Republicans been more supportive of his agenda, or at least allowed the Senate to hold votes on it, the economy would likely be in better shape and Obama would be in a far better position for re-election. From that perspective, obstructionism has been a net political plus for the GOP.

But obstruction is not opposition, and this is where Republicans have left the door open for Obama. By giving the president no support for even the smallest bits of legislation (including programs they once supported) and by not even allowing votes in the Senate on the president's agenda, they went from loyal oppositionists to relentless and partisan scolds – a point brilliantly reiterated by former President Clinton in his speech at the Democratic convention Wednesday night.

This is the downside to the GOP's four-year scorched-earth policy. By adopting such extreme anti-Obama positions, by taking the stance that any and all efforts to use the resources of the federal government to grow the economy are incipient socialism, and by making the political defeat of Obama, rather than just his policies, the party's central priority has opened up Republicans to the charge that they have been needless obstructionists who had no plan of their own for fixing the economy. It's hard not to see Romney's failure to offer any serious policy proposals for turning the economy around at his own convention as evidence of a party that refuses to contemplate any policy that doesn't include cutting taxes or shrinking regulation.

So the same radical anti-government forces that push Republicans to reject every element of President Obama's policy agenda also make it impossible for the party's standard-bearer to offer voters anything more than empty platitudes.

Far worse, the GOP has learned the hard way that, metaphorically, if you lie down with dogs, you get fleas. Implicit acceptance of the far right's narrative of Obama as an America-hating socialist has activated the GOP's most radical wing of voters. Republicans took a position not simply of implacable hostility to Obama's policies, but to the man himself. As these extreme voices have increased their influence within the party, they've moved Republicans further and further to the uncompromising right on a host of issues – from immigration to birth control and abortion – forcing their party's nominee to take policy positions that alienate even those voters disappointed in Obama's economic performance and inclined to look elsewhere.

Perhaps the greatest cost of this approach is that while polls show that voters believe Romney would be a better steward of the economy, they view Obama as someone who is more likely to favor the middle class and is more in touch with the challenges that affect them directly. That reservoir of trust, combined with the GOP's paucity of ideas, might just be enough for Obama to slide in for a second term.

Finally, by adopting such stridently oppositionist positions, not just against Obama but against the notion that the federal government had any responsibilities beyond shrinking itself into oblivion, Republicans have provided a boost to the Democrats' vision of government. Voters may still recoil habitually at the idea of big government, but they almost certainly recoil even further from the uncompromising alternative offered by the GOP. In desperate pursuit of political advantage, they have given Obama and the Democrats an opportunity to capture the political middle and redefine liberalism in terms that make it more palatable to a broad cross-section of voters.

This is only one part of the long-term damage. By adopting stances of such rigid ideological purity, by needlessly offending the fastest growing minority groups in the country, as well as young voters, and, finally, by basing the party's short-term renaissance on the oldest and most reactionary voters, Republicans have left themselves in a political no-man's land, should they lose this election. Rebuilding a party that has bet its entire political future on unceasing hostility to Obama will not be so easy. In the end, Republicans placed all their chips on seeking to defeat Obama's agenda and, above all, Obama himself. That opposition has brought with it consequences that might not only backfire on election day, but may well also ensure that the GOP spends more than just four more years toiling in the political wilderness.

For Obama, Republican hostility has left him bruised and in far worse shape politically than perhaps he should be in. But as he gives his acceptance speech at the Democratic national convention, he has the opportunity to turn the tables on those who have sought so lustily to thwart him. I'm guessing he won't miss the opportunity.