A Republican congressman said he's not sure that workplace discrimination against lesbian, gay, bisexual and transgender people exists -- because he's never gotten a phone call about it.

"I'm not even sure that this is a problem. I have to be honest, I don't get many, if any. I don't know that I've ever received a phone call in my office from somebody that says they've been discriminated against based on their sexual orientation," Rep. Kevin Cramer (R-N.D.) told Bismarck station KFYR on Tuesday.

Cramer is a first-term member of Congress who is facing a challenge from Democrat George Sinner. On Monday, the White House announced officials would draft an executive order that would bar federal contractors from discriminating on the basis of sexual orientation or gender identity.

Cramer added that he believes the White House's move was meant for political gain, and companies should be left to set their own policies.

Studies have found that workplace discrimination is a persistent problem for many LGBT individuals. Roughly one in five LGBT adults surveyed by the Pew Research Center in 2013 said that they had been unfairly treated by an employer.

Ninety percent of transgender people say that they have faced harassment in the workplace because of their gender identity, according to one study. In the same poll, 26 percent of transgender Americans surveyed said that they had lost a job because of their gender identity.

In just one instance of discrimination that Cramer apparently didn't hear about, in 2010, coal miner Sam Hall filed a lawsuit against coal company Massey Energy, alleging that another miner spray-painted a picture of Hall engaging in a lewd act and attached a sign to his car accusing him of being a pedophile. He later left the mining industry.

The Senate has passed the Employment Non-Discrimination Act -- which would extend federal protections against workplace discrimination on the basis of sexual orientation or gender identity -- but it has yet to be taken up by the House. Other efforts, however, have been more successful.

The Equal Employment Opportunity Commission said in 2012 that discrimination on the basis of gender identity violated Title VII of the Civil Rights Act. That opinion was delivered in response to the case of transgender woman Mia Macy, who alleged she was denied employment with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives because of her gender identity. Advocates have said that this decision could offer transgender individuals significantly greater protection against employment discrimination.

According to the Human Rights Campaign, 21 states and the District of Columbia have passed laws prohibiting employment discrimination on the basis of sexual orientation, and 18 states and D.C. also bar discrimination based on gender identity.