The Liberal Democrats say they will tax big tech to finance a new online crime agency, as they try to address concerns that not enough voters know what the party stands for.

The plan, to be announced at the party conference on Monday by the Lib Dems’ home affairs spokesperson, Max Wilkinson, would create a new Online Crime Agency focused on offences including child sexual abuse material, trafficking in drugs and weapons, and deepfake AI-generated pornographic images.

The planned budget of £250m a year would be paid for by an “online crime levy” on large AI and technology companies. Wilkinson is to tell the conference it is “time they picked up the bill” for offences they had enabled.

Ed Davey, the party leader, on Sunday set out a proposal to cut fuel duty by 10p a litre for a fixed three-month period, as well as reducing the bus fare cap from £3 to £1 and other transport-related cost of living policies.

The party is increasingly concerned that, although it won its best election result in a century in 2024, it does not have a distinctive enough message to reach voters in an increasingly fragmented and noisy political landscape.

Polling conducted to coincide with the conference in Brighton, released on Sunday, showed Lib Dem policies are less well known than those of Restore Britain, which launched as a political party only in February and has one MP – Rupert Lowe – compared with the Lib Dems’ 71.

The research by More in Common, which was presented at the conference, showed widespread uncertainty among voters about what the Lib Dems stood for. Just 39% said they had an idea, lower than for every other major party, including Restore Britain, which was formed by Lowe after he split from Reform UK.

Other parts of the research showed just 16% of voters said they had heard from the Lib Dems in recent months, against 66% for Reform, while 3% said they had seen Davey on social media, compared with 20% for the Reform leader, Nigel Farage.

In a round of media interviews on Sunday morning, Davey pushed back against the idea that the Lib Dems, who are static in national polling at about 12%, risked being forgotten in the political conversation amid the rise in prominence of Reform and the Greens.

His party, Davey insisted, was making a genuine difference, and not just generating coverage without substance.

“I’m talking about real change, not just talking about the bubbles,” he told the BBC’s Sunday with Laura Kuenssberg show. “We have been winning council elections for eight years in a row. That has never happened before – it’s the most successful period that we’ve had.”

While there is no talk among Lib Dem MPs about a challenge to Davey, some say they are frustrated the party’s message is too vague and its support too reliant on tactical voting in a limited number of places, mainly in the south of England.

One Lib Dem MP told a conference fringe event, at which More in Common’s findings were presented, that the party needed to expand the geographical and social range of its influence.

“If we want to be a party of government, then we need to have a message for the whole country, not just parts of it,” said Tom Gordon, the MP for Harrogate and Knaresborough, one of just four Lib Dem-held seats in the north of England, against 58 in the south.

Party figures see the conference as a chance to set out a more coherent and striking policy platform, including on the economy and immigration.

But there is worry among some MPs that the problem is wider. “We already have quite a lot of policies, if people look at them,” one said. “It’s less about what you get if you vote Lib Dem than why you should – about what we represent. And people don’t really know that.”

One longtime party activist said: “The voters only seem to properly notice us once every four years, when there’s an election. It’s a bit like being curling at the Winter Olympics – the rest of the time we’re forgotten. It would be good if we had a more distinctive message, and that needs boldness.”