The first cross-party campaign to condemn Nigel Farage's party as racist is to be launched this week amid fresh polls showing Ukip may come first across England in the European elections in May.

The campaign is led by the former Labour immigration minister Barbara Roche, who claimed: "Ukip's campaign needs to be exposed for what it is, a racist campaign. The party is practising what is in effect a form of 'Euracism'. They are deploying the same language and tactics used by openly racist parties like the BNP, but instead of targeting migrants from Africa and Asia they are targeting migrants from within the EU."

Labour and Tory jitters over the rise of Ukip – which led European election opinion polls for the first time over the weekend – are manifesting in an increasingly public debate in both parties about whether to attack it or oppose its anti-immigration policies.

It comes as one Europe-wide study suggested that anti-EU parties such as Ukip could win more than 30% of the vote across the continent next month. Calculations by the Open Europe thinktank suggest hardline sceptics could take as many as 218 of the 751 seats available – although this conclusion was has been challenged by other analysts. A second poll put Ukip neck and neck with Labour in England, but trailing in Scotland and Wales.

The new anti-Ukip campaign, backed by social media and posters, is supported by the all-party Migration Matters Trust. Migration Matters is co-sponsored by the Conservative Nadim Zahawi and by the Liberal Democrat deputy leader in the Lords, Lord Dholakia.

Roche said: "It is no less offensive to say British families should be wary of Romanians moving in next door than it is to say it of Nigerians or Indians.

"Every day another example of Ukip racism is exposed, and every day Nigel Farage attempts to dismiss it with the same lazy 'few rotten apples' argument. It won't wash.

"The likes of Andre Lampitt and William Henwood haven't stumbled into supporting Ukip by accident. They see a direct correlation between their own extremists views and those of the party they have been campaigning for."

Lampitt, who featured in a Ukip election broadcast, was suspended from the party after a string of Islamophobic tweets emerged. Henwood was condemned when he said the comedian Lenny Henry should emigrate to a "black country" and compared Islam to the Third Reich.

Roche has picked up on claims by Farage in the Guardian that British people should be wary of Romanians moving into the street. Roche's approach is controversial since critics claiming any attempt to brand Ukip as racists is in effect branding its apparently growing supporter base as racist. Polls have shown most voters do not regard the recent controversial Ukip posters as racist.

A second former home office minister, Jacqui Smith, said she was apprehensive about branding Ukip racist. Recalling Gordon Brown's attack on the Rochdale pensioner Gillian Duffy, she said: "Did we not learn from 'bigotgate' in 2010 that there are many potential and actual Labour voters who feel all the frustrations and insecurities expressed by the Ukip poster campaign? Telling them they are wrong – and worse, closet racists – is unlikely to win their support".

She said some of the sentiments in the Ukip poster reflected Labour policy.

The debate inside the Labour leadership about how to counter Ukip is reflected in a live debate about whether Ed Miliband should attack its leadership or acknowledge that Ukip support reflects a deep-seated unease about immigration and distrust of the political class. He is due to launch the party's European election campaign this week. So far its campaign has focused on the crisis of living standards.

Concern in the Tory mainstream about Ukip is also expressed today by the Bright Blue thinktank. Its head, Ryan Shorthouse, said David Cameron should "firmly reject" pressure to align the Conservative party more closely with Ukip or to adopt its policy agenda.

He said the Tory party only thrived when it offered an optimistic vision about the future of Britain, adding that the party had a good story to tell about the economy. Shorthouse said: "The Conservative party should firmly reject calls to be more closely aligned with Ukip or their policy agenda. Conservatives should fight the negative and divisive politics of Ukip, not pander to them. On immigration, the government should seek to convey competence: that it is properly managing our borders at the same time as ensuring businesses and universities can recruit the brightest and the best from around the world."

There are signs that senior Conservative ministers are starting to attack Ukip directly, something Conservative headquarters had wanted to avoid in case it alienated Ukip voters and made it more difficult to win them back to the Conservative cause in time for general election.

The latest poll commissioned by two universities and the thinktank IPPR, published on Monday evening, shows Ukip only one point behind Labour in England.

The polling, conducted by YouGov among more than 6,700 voters between 11 and 22 April, shows Labour on 30, Ukip 29 and the Conservatives 22. The polling shows Ukip's support varies widely. In contrast with its 29% showing in England, in Scotland it is at 10%, and in Wales, at 20%. The Lib Dems are the lowest placed of all the main parties everywhere.

The poll also reveals that Ukip's support is strongest amongst those in England that regard themselves primarily as English as opposed to British.

When people in England were asked which party and which political leader "best stands up for the interests of England", Ukip and Nigel Farage both came out on top at over 20%. By contrast only 3% of survey respondents in Wales identified Ukip as the party that best stands up for Welsh interests, and only 1% in Scotland as the party that best stands up for Scottish interests.

Glenn Gottfried, from the Institute for Public Policy Research (IPPR) said: "These differences in outlook between England and Scotland could have an impact on the Scottish independence referendum.

"A strong performance by Ukip in May's European elections might encourage Scots into the yes camp if they read it as a signal England may vote to leave the EU in a future in-out referendum on Europe."

Calculations by the Open Europe thinktank– challenged by other analysts – suggest hardline sceptics could take a total of 218 (29%) of the 751 available seats, up from 164 out of 766 (21.4%) in the current parliament – 30% overall. Open Europe says this bloc ranges from mainstream governing parties to neo-fascists.