Nick Clegg has warned Lib Dem activists they must get used to protests now they are in power, in a speech to the party's spring conference in Sheffield.
Party leader Mr Clegg urged Lib Dem members to "hold your nerve", saying "with power comes protest".
Thousands of students and trade unionists are expected to stage a protest outside the conference later.
And some Lib Dems are expected to turn their fire on the deputy PM over the planned shake-up of the NHS.
In an emergency motion, former MP Evan Harris, a member of the party's influential federal policy committee, will call on Lib Dem ministers to resist the coalition's plan to give 80% of the NHS budget for commissioning services in England to GPs.
The motion says the government's aspirations for health "can be achieved without the damaging and unjustified market-based approach that is proposed".
It says the changes have never been Lib Dem policy and were not in the coalition document agreed with the Conservatives when forming a government last May.
Mr Clegg has attempted to play down potential conflict with the party membership over the NHS, saying it was not going to be "the gunfight at the OK coral" and there was common ground.
But if the party conference backs the motion in a vote on Saturday morning, he will be expected to reflect their concerns at Westminster.
There is anger on the left of the party about what it sees as the handing over of key NHS assets to private firms.
The motion calls for the "complete ruling out of any competition based on price to prevent loss-leading corporate providers under-cutting NHS tariffs".
Lib Dem activists may have to run the gauntlet of anti-government protesters on Saturday. On Friday, several hundred people gathered outside Sheffield City Hall, which is surrounded by a £2m "ring of steel" and a heavy police presence, to chant anti-Lib Dem slogans.
Thousands are expected to take part in demonstrations against the Lib Dems on Saturday.
In a curtain-raising speech at Sheffield City Hall, Mr Clegg acknowledged it was "difficult" for the party to be the focus of protests, because "some of our proudest moments have come on marches".
He said: "We've put down our placards and taken up the reins of power. It's a big change but it's worth it.
"You can't do everything when you are in power, but you can't do anything when you are not. With power comes protest. We need to get used to it."
Party chairman Tim Farron also rallied the troops with a speech packed with jokes - some at the expense of the party's coalition partners the Conservatives.
Hitting back at jibes that the Lib Dems have become Conservatives since forming the coalition, he told activists: "I share a bed with my wife - it does not make me a woman."
The party is using its weekend in Sheffield to assert its independence from the Conservatives, amid fears it is losing its identity.
Both Mr Farron and Mr Clegg attacked Labour for what the two men claimed was their opportunistic approach to opposition.
Shadow Chancellor Ed Balls, for Labour, said he could not work with Mr Clegg in a coalition - echoing the words of Labour leader Ed Miliband during the party leadership contest last year.
In an interview with The Guardian, Mr Balls called Mr Clegg "an increasingly desperate, shrill and discredited politician" and says it would be impossible for Labour to work with Mr Clegg - "but that is not true of Liberal Democrats more widely".