The president ordered the Department of Health and Human Services to prohibit discrimination in hospital visitation. The memo is scheduled to be made public Friday morning, according to an administration official and another source familiar with the White House decision.

An official said the new rule will affect any hospital that receives Medicare or Medicaid funding.

The decision injects the president squarely into the debate over gay marriage by attempting to end the common practice by many hospitals of insisting that only family members by blood or marriage be allowed to visit patients.

Gay activists have argued for years that recognizing gay marriages would ease the emotional pain associated with not being able to visit their partners during a health crisis.

By contrast, opponents of gay marriage have said the visitation issue is a red herring, and have argued that advocates want to provide special rights for gays and lesbians that others do not have.

The memorandum from Obama to HHS SecretaryKathleen Sebelius, made public late Thursday night, orders new rules that would ensure hospitals "respect the rights of patients to designate visitors."

Obama says the new rules should require that hospitals not deny visitation privileges on the basis of sexual orientation or gender identity.

"Every day, all across America, patients are denied the kindnesses and caring of a loved one at their sides whether in a sudden medical emergency or a prolonged hospital stay," Obama says in the memo.

Affected, he said, are "gay and lesbian American who are often barred from the bedsides of the partners with whom they may have spent decades of their lives -- unable to be there for the person they love, and unable to act as a legal surrogate if their partner is incapacitated."

Obama's actions are the latest attempt by his administration to slowly advance the agenda of a constituency that strongly supported his presidential campaign.

In his first 15 months in office, Obama has hailed the passage of hate crime legislation and hosted the first gay pride day celebration at the White House. Last month, Obama's top military and defense officials testified before Congress in favor of getting rid of the "don't ask, don't tell" policy for gays in the military.

But the moves have been too slow for some in the gay community, who have urged the president to champion their causes head-on. One prominent gay blogger, John Aravosis, wrote last October that Obama's "track record on keeping his gay promises has been fairly abominable."