The minister for small business, Andrew Griffiths, has resigned from government after sending text messages of a sexual nature to two female constituents.
The contents of the messages were revealed in the Sunday Mirror.
Mr Griffiths, MP for Burton, and Theresa May's chief of staff in opposition between 2004 and 2006, told the Mirror he was "deeply ashamed".
His behaviour had caused "untold distress" to his wife and family to whom he "owed everything", he said.
Mr Griffiths also apologised for the "deep embarrassment" caused to the prime minister and the government, in a statement made to the newspaper.
The MP had been following the two women on Snapchat for six months before making contact in June.
Imogen Treharne, 28, told the Mirror the messages began one evening, after she posted a "racy" video.
Mr Griffiths told the barmaid he believed one video in particular had been uploaded "for him to react", Ms Treharne said.
Across Facebook, Instagram, WhatsApp and Snapchat, Mr Griffiths reportedly sent more than 2,000 messages in three weeks to Ms Treharne and another woman.
Ms Treharne said she "always asked him about his interests" but that the conversation "always turned back to sex".
She described the contents of the messages she received as "vile" and "disgusting".
Mr Griffiths said he has referred himself to the Conservative Party's Code of Conduct procedures following discussions with the chief whip.
BBC political correspondent Iain Watson said Mr Griffiths, who decided to resign on Friday night, "jumped before he was pushed".
Mr Griffiths, 47, an MP since 2010, became a father in April when his wife gave birth to a baby girl.