The Deputy Prime Minister will hail the by-election victory in Eastleigh as proof that the Lib Dems can succeed as a party of government.
He will also dismiss the "myth" that being in coalition has undermined their identity or ability to fight the Conservatives.
The rallying cry comes in a keynote speech to the Lib Dem spring conference in Brighton.
The leadership has been eager to use the gathering to move on from damaging allegations of sexual harassment by Lord Rennard - which he denies - and the conviction of former Cabinet minister Chris Huhne.
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PM spokesman's comments come following reports that the EU is secretly drawing up plans for greater military cooperation across the EU.
The Labour politicians put their alleged differences aside to jointly highlight how remaining in the EU could help fight climate change.
Late sunshine here and there this evening - but more cloud for southern Scotland, northern England and Northern Ireland again.