Barely a month ago the Conservatives gathered in Birmingham for their annual conference and heard the news that Mark Reckless, the MP for Rochester and Strood, had defected to UKIP.

One thing almost everyone agreed was that this was not going to be another Clacton – where Tory to UKIP defector Douglas Carswell won with a landslide vote.

>> Our full analysis of the Clacton and Heywood byelections

For the far right racist populist UKIP, the more Tory defectors it can return to Westminster as its own MPs at byelections, the greater momentum it will have as it launches a serious general election campaign for the first time in May. Rochester and Strood is important for its strategy – and a key test.

But David Cameron assured the press that the polls showed the Conservatives would win in Rochester and Strood.

Lynton Crosby, the political strategist, assured Tory MPs that Rochester wasn’t Clacton – its voters were younger, better educated, more cosmopolitan. And if that wasn’t enough Mark Reckless was a maverick – he was no Douglas Carswell.

Cameron unveiled tough plans to restrict immigration from the EU and denounced immigration in ever-shriller tones, all in a desperate attempt to halt the forward march of UKIP. Shamefully, Labour also responded to UKIP’s Clacton win – and the very narrow result in Heywood and Middleton – by tailending the immigrant-bashing agenda too.

Over the past four weeks Tory central office has used every trick and thrown everything at Rochester in order to win.

The Conservatives pushed the byelection back to November, giving the Tories more time to marshal their forces and plan their campaign. Ministers and MPs visit the constituency every day and hundreds of Conservative activists have been bussed in to campaign on the doorsteps.

The Tories thought they would defeat Mark Reckless in Rochester and Strood. But their complacency seems to have been badly misplaced. In Rochester, as in Clacton, UKIP is making hay out of discontent with the government and the mainstream parties.

At the beginning of the week Lord Ashcroft published a poll on voting intentions in Rochester and Strood:

UKIP – 44%
Conservatives – 32%
Labour – 17%
Lib Dem – 2%

Three other recent polls have put UKIP on an even bigger lead. It is bad news for anti-racists.

There are a couple of other findings of the Ashcroft poll that will be of interest to readers of this blog.

The first is that UKIP is rapidly professionalising its election machine. The Ashcroft survey found that 81% of Rochester voters have had literature, direct mail, visits, telephone calls or emails from the Conservatives – but 84% said the same of UKIP.

Labour had reached just under two thirds of voters (63%) and the Lib Dems less than a quarter (24%). This confirms what many activists on the ground have been saying – and the warnings by political commentators, such as Channel 4 News’s Michael Crick, ahead of the Clacton and Heywood polls – that Labour has given up on Rochester and Strood.

This is in a seat where Labour took 28% of the vote at the 2010 general election. Boundary changes rearranged the area before the 2010 vote – until then, the former Medway parliamentary seat had been held by Labour since 1997.

The second point is about a significant switching of Labour voters to UKIP. The Ashcroft poll suggest 40% of those who voted Labour in 2010 are now backing UKIP. For comparison, 44% of 2010 Tories have followed Mark Reckless to UKIP.

This highlights the danger if Labour does not fight UKIP and present a genuine alternative to voters who are angry after five years of Tory-Lib Dem government – it will lose its own supporters to the far right racists.

Though Mark Reckless looks set to be returned to parliament next Thursday, the evidence is that he can expect a battle next May. Of those naming a party, 36% of Rochester voters said they would probably vote Conservative at the general election, 35% UKIP and 21% Labour.

Just under three quarters (72%) of UKIP by-election voters said they would stay with their party next year, with 11% saying they would switch to the Tories and a further 11% saying they did not know what they would do.

While Ed Miliband and Labour have been under fire in the media for the past two weeks, the next few are going to be just as hard for David Cameron and the Conservatives. Ministers have privately warned the press that the party will face a crisis if it is unable to halt UKIP’s momentum by defeating Mark Reckless.

One minister told the BBC:

Just as night follows day, if UKIP wins in Rochester, there will be further defections.

This is what UKIP hopes for as it looks towards May. This is a very grim prospect.

>> Our full analysis of the Clacton and Heywood byelections