An extra 10,000 police on the streets would help stamp out the fear of crime, says Lib Dem leader Charles Kennedy.
The Lib Dems want police to spend more time on patrol
He launched his second full week of campaigning by focusing on crime and his plans for extra police and 20,000 more community support officers.
The Lib Dems also stressed their pledge to scrap plans for identity cards.
The Tories promise an extra 40,000 police, while Labour pledge dedicated police teams for every area and a total of 25,000 community support officers.
Mr Kennedy said his party's law and order package was based on "visible policing" to help stop the fear of crime undermining communities.
"Seeing a police or community support officer on patrol provides positive reassurance and an effective deterrent to would-be criminals," he said.
The Lib Dems would fund the extra police partly by scrapping the government's ID cards scheme, which they describe as flawed.
As well as boosting police numbers, they plan to cut police paperwork by providing officers with hand-held computers and speech recognition technology devices.
Mr Kennedy said that in an eight-hour shift, the average police officer only spent about 90 minutes on patrol.
"We need our police officers out in the community, not stuck in the station," he said. "We need to shift that balance."
Labour says its plans will produce strong community policing. And it says ID cards are important for tackling serious crime, abuse of the immigration system and illegal working.
Britain's most senior police officer, Sir Ian Blair, on Sunday said ID cards could be "very helpful" in the fight against international terrorism - an intervention criticised by the Lib Dems.
Home affairs spokesman Mark Oaten said the Metropolitan Police commissioner should "tread carefully", adding that Sir Ian was "wrong" in his opinions.
"It's my judgement that if Sir Ian was given the option of having additional police for the Met area or a piece of plastic ... that would be a more effective way of tackling crime in the area."
The Conservatives say the Lib Dems are "soft" on crime.
Home affairs spokesman David Davis said: "They want to scrap mandatory sentences for murderers and repeat rapists and allow these criminals to vote in elections.
"On top of this, their plans for 10,000 more police come out of scrapping a scheme that doesn't even exist yet. Our commitment to recruit 40,000 more police is fully costed."
Charles Kennedy will be interviewed by Jeremy Paxman in the first of a series of interviews with the major party leaders to be broadcast on BBC1 at 1930 BST on 18 April.