Editor's note: Timothy Stanley is a historian at Oxford University and blogs for Britain's The Daily Telegraph. He is the author of "The Crusader: The Life and Times of Pat Buchanan."
(CNN) -- A new CNN poll shows that it's back to a toss-up for the 2014 midterms elections. A month ago, Democrats were comfortably ahead 50-42%. Now the Republicans are marginally ahead 49-47%: a 10-point swing in public opinion.
Of course, the figures don't actually tell us who will win the next round of congressional elections, but they do remind us of a fact that escapes short-termist political punditry: Voters react to events and are liable to change their mind. The rise and rise of President Obama's unbeatable rainbow coalition is not a historical inevitability but the product of temporary trends.
To recap, the story a few months ago was that the Republicans had proved themselves incapable of governing wisely and, therefore, of winning elections. By trying to use the shutdown to force a delay in the further implementation of Obamacare, they were accused of putting partisanship before country, of pushing America to the brink of destruction just to humiliate Obama.
Their humiliation when the shutdown ended was shown in polling across all demographics. Eight in 10 voters disapproved of the shutdown, including two in three Republicans or independents who lean Republican.
But Democratic triumphalism was short-lived. The latest polling showing a turnaround was prefigured by two election results that showed residual conservative strength. In one, Chris Christie won a massive 2-1 victory that saw him make significant inroads into groups thought to be beyond the right's reach: women, Hispanics and African-Americans. In another, an unpopular ultraconservative Republican, Ken Cuccinelli, lost his gubernatorial race in Virginia but only by a small margin, despite being hugely outspent.
Christie's win was probably driven by his personal appeal to voters, but while only 27 percent saw the health law as the top issue, the outcome of the Virginia contest may well have been influenced by public annoyance over the botched rollout of the Obamacare exchanges. And it would be entirely justified by the trouble with the website and the disappointing discovery that millions could lose their existing coverage in spite of what the President repeatedly -- repeatedly -- told them.
In other words, while the public turned against the Republicans over the shutdown, they just as easily - and quickly - turned against the Democrats over health care. Crucially, the health care issue has a more direct impact upon their lives, which means its long-term resonance is likely to be greater. Obama's approval rating is now at its lowest since he took office, which also confirms the scale of the disaffection, and gives hope to the GOP.
The conclusion at the National Journal is that, "Race-by-race polling conducted over the last month has painted a grim picture of the difficult environment Senate Democrats are facing next year."
Of course, this doesn't mean things can't swing back the other way. The key word in all this data seems to be "volatility." Voters are fed up with Congress and disappointed in Obama. Who ends up benefiting from the misery will be down to events and good timing.
Either way, the idea that Barack Obama established a new New Deal coalition in 2012 that can't be broken by conservative politicians is clearly nonsense.
The opinions expressed in this commentary are solely those of Timothy Stanley.