WASHINGTON — Chief executives from 21 companies gathered at the White House on Friday, bringing with them a pledge not to unfairly weed out the long-term unemployed in their hiring process.

About 300 businesses signed the document, which promises not to discriminate against job applicants solely because they have been out of work for extended stretches.

The companies also agreed to ensure that their hiring practices don’t “intentionally or inadvertently disadvantage individuals from being considered for a job based solely on their unemployment status,” according to the pledge.