Critics have raised doubts over the Tory vow to hire 20,000 police after the target was almost 5,000 short with six months to go.
Boris Johnson promised to recruit the “uplift” by March 2023 in a key election pledge - nearly undoing years of cuts by his party.
But the number of extra officers found through the uplift rose from 11,277 in October 2021 to just 15,343 by the end of September - or 370 a month.
If the same rate of increase continued, it would still be more than 2,000 police officers short of the target by the end of March.
The Home Office said it did not “recognise these speculative calculations” and it remains on track to recruit 20,000 extra officers by the end of March 2023.
But the Lib Dems claimed the Tories are “on track to break their promise”.
Home Affairs spokesperson Alistair Carmichael said: “A broken promise on police numbers is yet another example of tough talk on crime but no action.
“This Government is failing victims of crime and letting far too many criminals get away with it.
“ Rishi Sunak is too mired in sleaze and chaos to have anything to offer to tackle crime.”
Each force has been given an allocation of officers to recruit through the uplift, with 6,000 to be recruited in each of the first two years and 8,000 in the third year.
But analysis by the Lib Dems showed the total number of officers had actually fallen in six months across a dozen police forces.
Lincolnshire had 37 fewer officers in September than in March, while Cumbria was down 28, Warwickshire was down 26 and North Wales was down 20.
Ministers insist 11 forces including the Met Police, Cheshire, Essex, Norfolk and South Wales now have the highest number of officers they have ever had.
Home Secretary Suella Braverman told MPs before Christmas: “The police workforce is more representative than ever before.
“For the first time ever, there are over 50,000 female officers (50,364), as at 30th September 2022, 34.9% of all officers in post.
“There were 11,477 ethnic minority officers, as at 30th September 2022, 8.2% of all officers in post the highest figures on record.”
The Home Office said some forces run the majority of their recruitment at a particular point in the year, meaning the rate of increase is not the same in every month.
A Home Office spokesperson said: “Our absolute priority is cutting crime and making our streets safer and we are providing police forces the resources they need to do this.
“We do not recognise these speculative calculations. The Police Uplift Programme remains on track to deliver an additional 20,000 police officers, by March 2023.”
