Nick Clegg will insist that he and David Cameron are both "absolutely committed" to governing in coalition through to 2015 as he attempts to calm speculation over the future of the power-sharing deal.
But he will dismiss talk of an early break-up of the Conservative / Liberal Democrat administration and call for a refocus on the economy.
Suggestions that the coalition could split before the 2015 general election were fuelled at the weekend by an interview in which the prime minister raised the prospect of governing alone.
Cameron told Total Politics magazine that despite some "frustrations", the coalition remained the best way to get things done.
"But if that wasn't the case then we'd have to face the new circumstances in whatever way we should,' he added.
Delivering a speech in Westminster, Clegg is expected to criticise what he calls the "rather creative coverage" of those comments.
"He echoed exactly what both of us have always believed: this Coalition has been remarkably radical; it still has work to do; and the best way for us to serve and improve Britain is by finishing what we started," he will say.
"I am absolutely committed to this coalition lasting until 2015 - as is the prime minister."
Claims that it was in either or both parties' interests to "prematurely pull the plug" were wrong, he will suggest.
Voters "will not forgive either party if we call time ahead of the election that has been legislated for in 2015 - destabilising the nation in the vague hope of short-term political gain".
Nor would it work for the Lib Dems to try to "pull the wool over people's eyes" and win back critics of the coalition deal by quitting six months early.
"And, frankly, that isn't what we want. The Liberal Democrats look forward to fighting the next election as a party of government, on our record in government, and with a distinct vision of our own for the next government - having seen this one through until the end."
Clegg will hit out at Tory MPs "obsessing over this new tactic or that new trick" after more than 100 backed an amendment criticising the lack of EU referendum legislation in the Queen's Speech and dozens attempted to scupper gay marriage reforms.
"Anyone watching would be forgiven for asking: what are these politicians doing?.
"So it's time to get back to governing; providing the leadership and focus the people of Britain deserve in these difficult times.
"Britain is facing the most profound economic challenge in living memory. And now, more than ever, we cannot allow Parliament to be clogged up by these matters simply because they cause the biggest political punch ups."
Senior Liberal Democrats are angry that major reforms to pensions and social care announced in the Queen's Speech and being led by the party's ministers have been lost amid the rows over Europe and gay marriage.
Clegg meanwhile has attracted the ire of many Conservatives by demanding a rethink of Tory-led flagship childcare reforms.
The Liberal Democrat leader will acknowledge that there are likely to be further disagreements between the parties but will insist he will not use them for political advantage.
Education secretary Michael Gove recently accused him of blocking the childcare changes to shore up his own party leadership.
"As we head towards the election there will be increasing pressure on David Cameron and myself to act as party leaders as much as PM and DPM: pressure to put party before nation," Clegg will say.
"And I don't pretend I won't relish the moment I can hit the campaign trail on behalf of the Liberal Democrats in the run up to the General Election.
"But here's the bigger truth: whether you are the larger or smaller party, the fact is governing together in the public interest carries a cost. Making compromises; doing things you find uncomfortable; challenging some of your traditional support - these are the dilemmas the Conservatives are coming to terms with, just as my party has had to.
"The next two years will not be without their hurdles and no doubt there will be disagreements between the coalition parties along the way. Let's be clear: sincere policy debates and ideological differences are, and will continue to be, a part of coalition.
"But the parliamentary game playing we've seen over the last few weeks discredits the importance of these issues, and it's an unwelcome distraction."
Despite being "staunch opponents", the coalition "remains united" on the central task of reviving the economy, he will say.
And it would stay rooted in the "modern, balanced, inclusive" centre ground" despite efforts by Tories to push the political agenda to the right or Labour to the left.