The website reported the photo upload to authorities, which led to an investigation at Folmer's home, a press release from Attorney General Josh Shapiro's office said. While there, investigators allegedly found photos of child porn on his phone.
Folmer allegedly told investigators he was working through "some personal problems" and admitted to receiving the child porn through his Tumblr account, PennLive.com reported, citing charging documents.
“This defendant serves as a state Senator and was entrusted to honor and represent his community in the Pennsylvania Capitol,” Shapiro said in a statement. “I will continue to say it — no one is above the law, no matter what position of power they hold. I will continue to work to protect children and hold those who abuse them accountable.”
Senate leaders on Wednesday said Folmer resigned following the charges.
“We elect leaders to serve as a voice for those who do not have the ability to advocate for their own needs, demanding that they will protect our children, families, and communities," Wolf said in a statement. "[The charges] show he has taken advantage of the trust and privilege afforded by the people of Pennsylvania. He should immediately resign.”
The Pennsylvania Senate's top leaders, Senate President pro tempore Joe Scarnati and Senate Majority Leader Jake Corman, said they were stripping Folmer of his chairmanship of the Senate State Government Committee.
“We are shocked to learn tonight of the allegations made against Sen. Folmer,” the senators said in a joint statement, according to The Philadelphia Inquirer. “We will fully cooperate with law enforcement regarding this deeply disturbing matter."
Folmer, who was elected to a fourth term in November, was charged with sexual abuse of children, possession of child pornography and criminal use of a communication facility.
Fox News has reached out to Folmer's office for comment.
Fox News' Bradford Betz contributed to this report.