Shadow business secretary Ken Clarke has told politics.co.uk he believes the Conservatives only have a "slim chance" of winning an overall majority.
Mr Clarke, speaking in the Labour-Tory marginal of Bedford, said his "hunch" was that the Conservatives would avoid a hung parliament. But he admitted that "I can't ignore opinion polls".
"I think there's a still a slim chance we can get an overall majority, which I would very much like to see," he said.
"It is very difficult to read because the electoral geography is quite local and it is a complicated breakdown of voting which is taking place - but my hunch is we're still in with a chance of getting a parliamentary majority."
Projections from most polls carried out since the final leaders' debate last week have suggested the Tories could emerge as the largest party in the Commons - without them crossing the 326-seat finish-line for an overall majority.
Mr Clarke said he had a "horror" of hung parliaments and the inevitable negotiations with other parties which would prevent the Conservatives from "getting on with the job".
"What we're plainly headed for would be a great deal of squabbling, with small parties given disproportionate influence, trying to manoeuvre advantages for themselves before they allow a Conservative government to get on with the job," he added.
"This is the gravest economic crisis we've had since the war. Recovery is not yet certain. The financial markets have been in a very fragile and nervous state.
"To sit and listen to a Conservative would-be government trying to negotiate with the Scots about how much less the public spending cuts are going to be north of the border, or with the Liberals about various tedious kinds of electoral reform, would I think be very reckless."
Mr Clarke, who introduced himself to one voter today by telling him "I was chancellor in John Major's government", is visiting four constituencies today as part of the Tories' last-minute efforts to win over wavering voters.
The shadow business secretary is already looking beyond polling day to the restrictions faced by a minority Conservative government, however.
"There would be really quite appalling consequences for this country if we are not able to produce a credible plan for dealing with the deficit and the debt. And that involves some very difficult decisions," he warned.
"If I have to sit and talk to three or four other groups... in the end you can always do a deal with an Ulsterman, but it's not the way to run a modern sophisticated society in the grips of an economic crisis which weak government under Gordon Brown has already caused."