(CNN) - Support for same-sex marriage has received a boost, according to a new CNN/Opinion Research survey released Tuesday.
The poll indicates that more than half of all Americans believe that marriages between gay or lesbian couples should be legally valid. With 51 percent of respondents saying that same-sex marriages should be legal, it is the first time that a CNN poll has found majority support for same-sex marriage.
Full results (pdf)
Although more Americans agree on this issue, a generation-and gender-gap still remains. Sixty percent of Americans under 50 support same-sex marriage, but only four in ten of those over 50 feel the same. More than half of men are against legalizing marriage between gay or lesbian couples, but 57 percent of women are in favor of it.
There's also a partisan divide on the issue. "More than six in 10 Democrats support same sex marriage, joined by more than half of independents, but seven in 10 Republicans are against it," says CNN Polling Director Keating Holland.
The poll comes out just after Speaker of the House John Boehner moved to hire a conservative lawyer to defend the federal Defense of Marriage Act (DOMA) in a pending lawsuit. The Obama administration said it believed that DOMA to be unconstitutional and would no longer have the Justice Department defend it in federal courts.
Generations are also split on whether marijuana should be legalized. Two thirds of older Americans oppose it and younger adults are split, with 49 percent in favor of the legal use of marijuana and 50 percent against it. Overall, only four in 10 Americans support decriminalizing pot, which is still more than double the number who favored it 25 years ago.
The CNN/Opinion Research poll was conducted among 824 adults by telephone from April 9-10. It has an overall sampling error of plus or minus 3.5 percentage points.
–CNN's Rebecca Stewart contributed to this report.