In order to claim donations on your tax return, the organization you donate to must be a registered, qualified charitable organization or NPO. The IRS has a list which you can check at https://www.irs.gov/charities-non-profits/tax-exempt-organization-search
Basically, if they are not on the list, then donations to them do not qualify for any type of tax deduction. You must also have the required documentation to support your claim that your donation is deductible. For the documentation requirements, see https://www.irs.gov/charities-non-profits/substantiating-charitable-contributions
Understand there are two basic types of charities/tax exempt organizations one can donate to. 30% type and 50% type. For a 30% type, only 30% of your donation or donation value is tax deductible. Ditto for a 50% organization.