The US Food and Drug Administration (FDA) has recommended the end of a three-decade ban on blood donations from homosexual and bisexual men.
However, some restrictions will remain, as the FDA said it favours replacing the blanket ban with a new policy barring donations from men who have had gay sex in the previous year.
Some gay activists have responded to the announcement by complaining it is unrealistic and stigmatises the LGBT community.
Having examined scientific evidence surrounding blood donation for men who have sex with men, the FDA said in a statement that it will recommend a change to the blood donor deferral period from indefinite to one year since the last sexual contact.
The current rule has been in place for 31 years and dates from the first years of the AIDS crisis, and was intended to protect the US blood supply from exposure to the little-understood disease.
Under the policy, blood donations are barred from any man who has had sex with another man at any time since 1977 — the start of the AIDS epidemic in the US.
But medical groups, including the American Medical Association, say that the policy is not supported by science, given advances in HIV testing.
Last month, a panel of blood safety experts convened by Department of Health and Human Services voted 16-2 in favour of ditching the lifetime ban, and recommended barring donors who have had male-on-male sex during the previous 12 months.
In the US, all donated blood is tested for HIV, however, the test only detects the virus after it's been in the bloodstream about 10 days - allowing a brief window when the virus that causes AIDS can go undetected.
If the new advice is put into place, US law will be put in line with other countries including the UK (except Northern Ireland), Australia and Japan.
Patient groups that rely on a safe blood supply, including the National Hemophilia Foundation, have also voiced support for dropping the ban.
But LGBT campaigners say it does not go far enough.
"Some may believe this is a step forward, but in reality, requiring celibacy for a year is a de facto lifetime ban," the organisation Gay Men's Health Crisis, a New York-based nonprofit that supports AIDS prevention and care, said after the announcement.
The FDA will publish its advice in draft guidelines early next year, and will move to finalise them after taking comments from the public, officials said.
FDA Deputy Director Dr Peter Parks declined to give a deadline for the process but said, "we commit to working as quickly as possible on this issue."
According to government figures, men who have had sex with other men represent about 2 percent of the US population, yet account for at least 62 percent of all new HIV infections in the US.
The recommendation is the culmination of a push for new policy which gained momentum in 2006, when the Red Cross, the American Association of Blood Banks, and America's Blood Centers called the ban "medically and scientifically unwarranted."
Additional reporting by AP