Nick Clegg is to make his first foray back on to the political front line in the wake of the Liberal Democrats' electoral drubbing.

The former Deputy Prime Minister will lambast the Tory government in the Commons for "turning its back" on the liberal stance adopted during the coalition years.

Mr Clegg, who clung on to Sheffield Hallam despite the Lib Dems losing 49 of the 57 seats it secured in 2010, will represent the party as the Commons debate on the legislative package opens.

A leadership to replace him at the helm is currently under way, with Tim Farron regarded as the favourite.

Mr Clegg is expected to tell MPs that the Lib Dem "mission" is "clearer than ever" even though its parliamentary presence has "reduced in size".

"The Liberal Democrats worked hard to ensure that the Coalition Government's agenda had a clear thread of liberalism running through it - from the priority we gave to mental health and the green agenda, to creating the pupil premium and protecting our civil liberties," Mr Clegg will say.

"So it is dispiriting - if pretty unsurprising - to see how quickly, instead of building on those achievements, the new Conservative Government is turning its back on that liberal stance.

"The human rights we hold dear, our right to privacy in an online age, our future as an open-minded, outward-looking country, are all hanging in the balance again because of the measures being announced by the Conservative Government."

Mr Clegg will go on: "My party's parliamentary presence may be reduced in size, but our mission is clearer than ever.

"As we did in the Coalition Government, we will fight any attempt to weaken the fundamental rights of our citizens.

"We will stand up for the poorest and the most vulnerable.

"And we will always defend a Britain that is at its best when it is open-hearted, open-minded and outward-looking."