Voters in the blue wall have seen an average of eight Liberal Democrat adverts as the party steps up its bid to oust high-profile names like Jeremy Hunt, according to sources.
The Lib Dems are climbing in the opinion polls, with some even suggesting they could be fighting for second place in the event of a Tory meltdown.
Forecasts indicate the party could take more than 50 seats on Thursday after a campaign noted for leader Sir Ed Davey’s stunts.
He has fallen into Lake Windermere to highlight the sewage problems in UK waterways and attempted to conduct an interview on economic policy while being spun around on a fairground Twister.
Mr Hunt, who has spent £100,000 of his own money trying to save his Surrey seat, concedes he is in trouble.
Recently he estimated that just 1,500 votes would define whether he won or lost.
The Lib Dem adverts are also being targeted in seats held by other top Tory names, including the education secretary Gillian Keegan and the justice secretary Alex Chalk, but there is no doubt replacing the chancellor would be a coup.
A Liberal Democrat source said that the party had focused on reaching people in blue-wall seats, Tory heartlands in the south of England, from the start.
“It’s vital in these final few days of the campaign that voters know that they need to vote Liberal Democrat to kick out the Conservatives in seats where we’re the main challengers,” they added.
“The results in many of these seats will be really close, it could come down to just a few hundred votes. The difference between the Conservatives clinging on and suffering a historic defeat will come down to how many people vote tactically in these seats and lend us their vote on the day.”
Party insiders fear younger voters in some seats are unaware that the Lib Dems are the main challengers to the Tories.
Older people who have lived in an area for a while are more likely to know who is second in their seat.
But the party’s fears centre on voters who have moved out of cities like London in recent years, especially after Covid.
These voters, often sympathetic to Labour, could switch to the Lib Dems, the party believes, but only if they are aware of which party is most likely to keep the Tories out.
In the first week of the campaign, party sources say they reached two million voters in its top blue-wall seats.
Digital ads have been seen over 40 million times since the election was called, while voters in blue-wall seats have seen a Lib Dem ad an average of eight times each so far in this campaign.
The party has also run more than 1,200 variations of ads targeting switch voters, largely with messages about the NHS.
In what has been dubbed the “TikTok election”, the Lib Dems have reached 4.7 million people, around 80 per cent of whom are under 35. It’s a key group for the party as a recent YouGov poll suggested almost one in four 18- to 24-year-olds say they plan to vote Lib Dem, sources said.
The Conservatives have been approached for comment.
