WASHINGTON — President Barack Obama plans to sign an executive order forbidding companies that do business with the federal government from discriminating against employees on the basis of sexual orientation or gender identity, fulfilling a goal that gay rights organizations have sought for years.

Currently, no federal law bans discrimination against gay and transgender individuals. Twenty-one states and the District of Columbia bar discrimination on the basis of sexual orientation, but in the remaining 29 states, employers are free to fire, demote or otherwise discriminate against workers solely on the basis of sexual orientation.

Obama had tried for the last several years to get Congress to pass an anti-discrimination law that would apply to most employers in the country. But with those efforts going nowhere, he has now directed his staff to draft an executive order that would ban discrimination by federal contractors, White House officials said Monday.