Lord Parkinson told the Neill inquiry into political funding that the shadow cabinet could not manage on the pounds 1.1m state funding it received.
The situation was so dire that when the Ministry of Defence flew Sir George Young to Bosnia but told him to pay his own return fare, Conservative Central Office was not sure how to fund the trip, he said.
"We were very worried he might not be able to get back again," he joked.
Lord Parkinson confirmed that the Conservative Party had raised so much money in the run-up to the last election that it had been able to pay off a pounds 19m overdraft and still spend pounds 20m on its campaign.
There was a "huge blitz" of "one-off" donations from people who felt it sufficiently important that the party should survive.
"We had a record level of expenditure and our worst-ever result.
"It shows that if the tide is running against you, no matter how much money you spend, you don't stem it. Therefore, in future the Conservative Party will be very much more careful about how it uses its resources," he said.
An atmosphere of greater openness about political donations would curtail gifts in future, he added. One donor, who had given six-figure sums in the past, had given pounds 4,500 this year after the party promised to disclose donations over pounds 5,000.
While the Government could spend pounds 2.6m on special advisers alone, the increasing demands on opposition parties meant the Conservatives' pounds 1.1m "short money" was not enough, Lord Parkinson said.
Mr Hague's office was funded largely by the state handout, but occasionally received gifts for particular projects, he said.
Sir George, the former shadow secretary of state for defence, who became shadow leader of the house last week, said in written evidence that the Ministry of Defence had been "as helpful as could be" over his trip to Bosnia.
"But it could not fly me back, and that had to come from other funds," he wrote.
The Conservative Research Department had been able to allocate support to the defence team of only "one-third of a person" despite a near-war with Iraq and the ongoing strategic defence review.