More than half of all Americans now say Lance Armstrong should not get credit for his career accomplishments in cycling, according to a new Washington Post poll.

The new numbers reveal a quick reversal in public sentiment about the seven-time winner of the Tour de France.

Just before he used a broadly publicized interview with Oprah Winfrey to admit — and attempt to explain — his regular use of performance-enhancing drugs, 45 percent said he should get credit for his accomplishments, and fewer, 37 percent, said he should not. Now, public opinion breaks the other way, with just 30 percent saying he should get credit and 51 percent saying no.

Armstrong has lost support across the board, both among sports fans and non-fans. Those 50 years and older are 3 to 1 against his getting credit for his cycling wins; they were evenly divided two weeks ago.

Adults under 30 are the least likely to have moved against Armstrong in the days after he back-tracked on fierce, aggressive denials of any rule-breaking. In a Washington Post poll earlier this month, young adults were the least apt to say they are bothered by professional athletes’ use of performance-enhancing drugs.

The new poll was conducted Thursday through Sunday, among a random national sample of 1,006 adults. Results have a margin of sampling error of 3.5 percentage points.

Armstrong’s interview with Oprah was recorded Monday and aired in full Thursday and Friday evenings on the Oprah Winfrey Network. Armstrong’s worst day in the poll was Saturday, at the likely point of peak coverage of the interview.

Cohen is director of polling for Capital Insight, the independent polling group of Washington Post Media. Craighill is a pollster with Capital Insight, as is Scott Clement, who contributed to this report.