Brad Parscale, digital director for U.S. President-elect Donald Trump, speaks at Trump Tower in New York, Dec. 3, 2016.

Parscale, now chief of Trump's 2020 campaign, spearheaded the president's digital media strategy in 2016. Trump originally hired him to build a website for his exploratory campaign in 2015. Parscale eventually took on a prominent role as a digital strategist, rising to become one of the campaign's central decision-makers.

"I think that when the left found out that Facebook, a tool built by Silicon Valley, helped elect President Trump, they weren't very happy," Parscale said. "And so they want to do everything they can to help prevent conservative voices. And I think that you have multiple platforms I call the 'Palo Alto mafia' trying to stop that."

President Donald Trump 's 2020 campaign manager, Brad Parscale, attacked social media companies Monday for allegedly squashing speech in an interview on the television program "CBS This Morning."

In the interview, Parscale credited the Trump campaign's dominance in Facebook advertising as being a key contributor to its success in 2016. He referenced the wide gap between the number of Facebook ads Trump and Hillary Clinton placed during the run-up to the election. Trump's team placed 5.9 million ads compared with Clinton's 66,000.

A Facebook spokesperson was not immediately available for comment.

Trump and his conservative allies in Congress have lashed out against the major social media companies for perceived anti-Republican bias. In August, the president wrote in a post on Twitter that Google was "controlling what we can & cannot see. This is a very serious situation-will be addressed!"

In April, Facebook CEO Mark Zuckerberg was questioned on the issue at a congressional hearing.

"There are a great many Americans who I think are deeply concerned that that Facebook and other tech companies are engaged in a pervasive pattern of bias and political censorship," Sen. Ted Cruz, R-Texas, said at the time. Zuckerberg told Cruz then that Facebook is a "platform for all ideas"

The companies have all said that they do not filter content based on political ideology.

Parscale claimed that even if social media companies exclude conservative ideas on their site, people will find other ways of spreading their ideas.

"There are lots of things they can't stop," Parscale said. "And I think one of the big emerging technologies is just your cellphone, direct, rich media and text messaging, and the things we can do directly through your phones."