Prime Minister David Cameron has urged people to consider a tactical vote to stop UKIP winning the crucial Rochester and Strood by-election.

In a tacit admission that the Conservatives could have to rely on other support from other parties if they are to win the crucial poll, he told the KM Group political editor Paul Francis it was now a two-horse race.

The PM visited the Medway Messenger office today on what is his fourth visit during the campaign.

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In what amounted to an appeal for voters to forge a cross-political alliance to deprive Ukip of securing victory, he said:

“The campaign is going to shape up in the next ten days into a very clear choice: you can vote for Ukip and be part of the national campaign and another notch for them in their development and then the great caravan will move on, or you can vote for Kelly, who is a hard-working, local person, born and raised locally.”

He added: “We have got to focus people on that choice. It is a two horse race; those are the only two real choices and we the more we can get people to focus on who is the right person for the job, with the issues that people are caring about, the more people we can get voting for Kelly.”

Mr Cameron's appeal for tactical voting came as a new poll put the Ukip ahead of the Conservatives by 12 points.

The poll by Lord Ashcroft put Ukip on 44%, the Conservatives on 32% and Labour on 17%.

The Greens are on 4% with the Lib Dems trailing on 2%.

The poll represents a small dip in Ukip support but still means the party is on course for victory on November 20.

Asked if he wanted people to consider tactical voting, he said: “I would say to people who have previously voted Labour, Liberal, Green or anything, that if you want a strong local candidate and don’t want some Ukip boost and all the uncertainty and instability that leads to, then Kelly is the choice.

“There is a real opportunity for people of different political parties to unite behind the local candidate and to say to the MP ‘we don’t like the way you behave; we don’t like this sort of politics we want to vote for the person who stands up for the area” - David Cameron

"By-elections are different; there is a chance for people to vote in way they haven’t done before."

Asked if he wanted Labour supporters to consider tactical voting, he said: “Yes, of course. I think there will be lots of Labour supporters in Rochester and Strood who don’t want to see Ukip with their divisiveness and their message succeed here.

"If you want a strong local candidate, then Kelly can be your tribute – she can be someone who stands up for the area.”

“You can see with Mark Reckless he is more interested in his own business, with what he is saying about Europe and all the rest of it; he’s interested in his future, whereas Kelly is interested in Rochester’s future.”

He denied that an appeal to supporters of other parties represented a weakness in the Conservative campaign.

“I don’t think so. I think in politics you should always try to reach out to other voters; you should never just rely on your base or core vote; every MP, every candidate, is always trying to win over new supporters.”

“There is a particular opportunity in a by-election, particularly one where you have got such a different campaign. Ukip is trying to make a national point; they are trying to make a disruptive campaign; it is not about Rochester and Strood, it is about them.”

“There is a real opportunity for people of different political parties to unite behind the local candidate and to say to the MP ‘we don’t like the way you behave; we don’t like this sort of politics we want to vote for the person who stands up for the area.”

Prime Minister David Cameron was making his fourth visit to Rochester and Strood today with just over a week before the by-election.

It's claimed the events of November 20 could have a far-reaching impact on the nation's political landscape.

Mr Cameron's schedule included a visit to the KM Group's head office at Medway, following a stop at Strood Academy, where he met students and staff.

During his visit to the Medway office, Mr Cameron spoke with our political editor Paul Francis about his party's prospects at the poll on election day, where Kelly Tolhurst is taking on Mark Reckless, who defected to Ukip.

While the polls have indicated the Conservatives continue to have a gap to close on Ukip, Mr Cameron has insisted that there is all to play for ahead of the election.

Video: Prime Minister David Cameron discusses the by-election