Private discussions held by George W Bush before he became president suggest he used marijuana, but would not admit it for fear of setting a bad example.
Bush was still governor of Texas when the tapes were recorded
Mr Bush said that his refusal to answer questions about illegal drugs might cost him the 2000 election.
The conversations were secretly taped by a former aide to Mr Bush's father who has now released part of them.
The White House has not disputed the authenticity of the tapes but spokesmen refused to comment on the contents.
"These were casual conversations that then Governor Bush was having with someone he thought was a friend and that's what they are," Scott McClellan said.
Another spokesman, Trent Duffy, told the New York Times the issue of Mr Bush's drug use had been "asked and answered so many times there's nothing more to add".
Dodging the question
As George W Bush, then governor of Texas, was weighing up a run for the White House, he held a number of private discussions with Doug Wead, a former aide to George Bush Senior, the former US president.
The conversations, which took place between 1998 and 2000, were recorded by Mr Wead without Mr Bush's knowledge.
The former aide has released parts of the tapes to coincide with the publication of his new book, The Raising of a President, though some remain private for legal reasons.
Mr Bush has spoken frequently about a drink problem in his youth, which ended with an apparent religious awakening at the age of 40, but he has never admitted taking illegal drugs.
On the tape, however, the future president discusses his refusal to answer questions about whether he took marijuana.
"I wouldn't answer the marijuana question," he says.
"You know why? 'Cause I don't want some little kid doing what I tried."
He feared that any such admission might affect his standing if he won the presidency.
"You gotta understand, I want to be president, I want to lead," he tells Mr Wead.
"Do you want your little kid to say 'Hey daddy, President Bush tried marijuana, I think I will'?"
In response to a remark by Mr Wead that the future president had publicly denied using cocaine, he said, quoted by the New York Times: "I haven't denied anything."
He said that he would continue to refuse to comment on allegations of drug use.
"I am just not going to answer those questions," he said. "And it might cost me the election."
'I won't kick gays'
In the tapes, Mr Bush mocks Al Gore, his opponent in the 2000 elections, for admitting to smoking cannabis, and also dismisses him as a liar.
The BBC's Michael Buchanan in Washington says that what is perhaps most remarkable about the conversations is how early Mr Bush realised the importance of reaching out to Christian conservatives.
Speaking in advance of a meeting with Christian leaders in September 1998, he is heard saying: "There are some proper ways to say things and some improper ways. I am going to say I've accepted Christ into my life. And that's a true statement."
And while standing in the Republican primaries in 1999, Mr Bush apparently ruled out Colin Powell and Tom Ridge as vice-presidential candidates because they favoured abortion rights.
But he refused to bow to conservative pressure on him to criticise homosexuals.
"I'm not going to kick gays because I'm a sinner. How can I differentiate sin?" he claimed on the tape to have told James Robison, an evangelical minister in Texas.