The Tories may not win the next general election, party chairman Grant Shapps has publicly conceded.
Shapps said the Conservatives would have to show "leadership and vision" if they were to stand a chance of gaining an outright majority in 2015.
However, in a clear warning to would-be leadership challengers, he stressed that David Cameron remained more popular in the country than the party as a whole.
Shapps also took a series of sideswipes at their coalition partners in the Liberal Democrats, calling them "cockroaches" and dismissing Business Secretary Vince Cable as a "commentator on the economy".
In an interview with Parliament's The House magazine, he sought to play down the Conservatives' poor showing in the
Eastleigh by-election when they were beaten into third place behind the UK Independence Party.
"Mid-term by-elections have a long, almost proud tradition in this country of having a protest party win," he said.
However Shapps, who is in charge of the party organisation, acknowledged there was no guarantee they would recover in time for the next general election in two years time.
"We may or may not win the next election but my God we need to finish this, the job of stopping this country going bust, fixing the mess that Labour left, or at least as far as we can," he said.
"If it's not finished, we will be asking to come back and finish it as a majority government. We need to show people we have the leadership and vision to do that."
He sought to play down reports that Home Secretary Theresa May was preparing the ground for a future leadership challenge, after she delivered a well-received speech setting out her political vision ranging way beyond her departmental brief.
"It was a very good speech. Sometimes parties get in power and they stop fizzing with ideas. We clearly have very clear passionate debates. I think it's really good for the party," he said.
"I think having peoples set out ideas is really important. It shows that we're healthy."
But amid growing unrest among Tory MPs, he warned against any attempt to unseat Mr Cameron.
"David Cameron is more popular than all of us ... more popular than all of the party in the country, which is a key point that lots of people do recognise," he said.
In a move apparently designed to boost party morale, he suggested the next election manifesto could include a commitment to restrict child benefit and other welfare payments to two children per family.
"I just think it's something we need to look at. I'm not writing the next manifesto now but it's an open question," he said.
"We live in a world where we all have to make decisions about where we live and how many children we have and the other things which impinge on the cost of living and having children is one of them.
"It's enormous and of course it should be a consideration."
With the Tories preparing for their spring forum at the weekend, he also took a series of crowd-pleasing swipes at the Lib Dems, picking up on Lib Dem president Tim Farron's suggestion that they had the resilience of cockroaches.
"I don't want to go any further than the president of the Liberal Democrats when I describe our Liberal Democrat partners in Government, and I will not be forced into a position of calling them anything worse than cockroaches," he said.
He issued a pointed reminder of the Lib Dems' abandonment of their election pledge to oppose any increase in university tuition fees.
"I know that some other political parties like to break their manifesto pledges, but we ain't doing it," he said.
He was particularly scathing about Mr Cable who has been pressing for a big increase in infrastructure spending in next week's Budget to kick-start economic growth.
"I was listening to the radio. Vince Cable was on and, you know, he was sort of a commentator on the economy and what have you," he said.
"If anybody wants to be a commentator, there are lot of newspapers who'll hire you but, you know, I consider that a Conservative Party and our ministers are here to lead the country through these difficult, choppy waters and, actually, through the coalition, in truth, to better times ahead.
"We've come together in the national interest, and we should be leaders in that, not commentating on every aspect and twist and turn."