Labour has hit back at claims that it is running a “mealy-mouthed” European elections campaign after new figures showed the party’s spending on Facebook ads was dwarfed by the Lib Dems, Change UK and Nigel Farage’s Brexit Party.

Jeremy Corbyn is under fire from his own MPs, who claim the party lacks a clear message on a second referendum and lacks the firepower to counter its rivals ahead of next Thursday’s poll, HuffPost UK has learned.

New data from the ‘People’s Vote’ campaign shows that from May 5 to May 11, Labour spent just £7,331 on Facebook advertising for the elections – less than a third of the Lib Dems outlay of £23,191.

Farage’s party spent the most with £26,776 and Change UK spent £21,490. The Conservatives spent just £2,286, the Greens £247 and Plaid Cymru £117.

Labour backbenchers also complain that the party has taken a cost-cutting option on its leaflets, is failing to produce enough online adverts and is actively stopping trade unions from delivering ‘People’s Vote’ campaign material.

By contrast, the Brexit Party has launched targeted ads aimed at leading Remain MPs in both Labour and Tory parties, including Margaret Beckett, Ben Bradshaw, Justine Greening, Jo Johnson and Dominic Grieve.

Corbyn admitted earlier this week to his MPs that he wanted “immediate” action to sharpen up the Labour campaign messaging in the run-up to the MEP elections next week.

Labour insiders have told HuffPost UK that critics were wrong to attack the campaign, claiming that the party was in fact spending more than it had ever done on any previous Strasbourg election.

One source added that the party has a greater reach online than its rivals and doesn’t need to produce as many adverts on Facebook and elsewhere that other parties do.

But some Labour MPs say that the Facebook spending figures fuel concerns that the party’s campaign lacks the energy, clarity and resources that helped Corbyn wipe out the Conservatives’ majority in the 2017 General Election.

They point to a YouGov poll this week that showed that 60% of Labour’s 2017 vote was now ready to back other parties. Almost four-fifths of it is going to parties, like the Liberal Democrats and the Greens, that are more clearly in support of a new public vote and remaining in the EU.

Labour’s membership (540,000 to 99,000) and budget (£56 million to £10 million) is more than five times greater than the Lib Dems, yet its Facebook spending on the Euro elections is lagging behind Vince Cable’s party.

While Labour has so far unveiled only four different online ads, the Brexit Party has sent out 36 different adverts.

Labour MP Ben Bradshaw said: “Every Labour campaigner who has been out on the doorstep knows the truth. Even though we have excellent candidates who are supporting a People’s Vote, our campaign is being hobbled by a lukewarm, mealy-mouthed, half-hearted policy on Brexit that leaves our voters either confused or angry.

“Labour’s members, voters and candidates in these elections are overwhelmingly behind a People’s Vote.

“It’s good that our party is committed to a public vote on at least the Tories’ Brexit deal, but the failure to deliver a clearer message about this or invest in a stronger campaign is in danger of delivering victory to Farage. That risks not only damage our party but also to our country.”

MPs are also unhappy that the party has chosen to send one leaflet to every household, rather than one to every voter in the European elections.

Under Freepost rules, parties are allowed one mailshot that is either addressed to individual voters or to a whole household. The taxpayer pays for the postage, but the cost of printing multiple leaflets is down to each party.

UKIP and the Brexit Party are the only parties to have opted for the per-elector leaflet, which lets them individually target an estimated extra 15 million voters, though at a price of potentially hundreds of thousands of pounds more than their rivals.

Several Labour MPs also claim that Corbyn allies in London have halted the national rollout of leaflets funded and printed in the South West by Unison and Usdaw, which urged voters to back “a public vote with Labour” rather than “Brexit chaos with Farage”.

The party’s own leaflet includes a reference to the ‘option’ of a public vote, but critics claim the mention is too small and confusing.

“Labour volunteers won’t deliver the official leaflets, they love ours,” one People’s Vote-backed MP said.

However party sources hit back hard at the criticisms, pointing out that Labour’s online ads reached many more people than its rivals and that it was spending its members’ money wisely in both online and offline campaigns. 

Regions were allowed to localise their messages, and the Facebook spending for early May was just a snapshot rather than a true reflection of overall spending, they added.

The party will amend its messaging in the next week for a major get-out-the-vote push ahead of poling day on May 23.

Corbyn supporters point out that polls have been mixed, with the party still ahead of the Lib Dems and Tories in most surveys – and even ahead of Farage’s party in one.

Labour’s main message for the elections is that it is the only party that can unify the country and defeat Farage.

Its two-pronged strategy is aimed at maximising the Labour share of the vote, but also targeting key marginal areas to help the party win seats at the next general election.