The government's chief whip has promised to investigate messages sent to a female Conservative MP by a colleague in which she was was called a "disgrace" and told to quit the party.
In a now-deleted tweet, Antoinette Sandbach shared a screenshot of WhatsApp messages which she said were sent to her by a male Tory MP.
"You too are a disgrace. Time you left the party I think," they read.
It comes as Conservative MPs voted for their final two leadership contenders.
On Thursday, secret ballots were held which whittled down the remaining candidates to just Boris Johnson and Jeremy Hunt - one of whom will become the UK's next prime minister.
Ms Sandbach, the MP for Eddisbury in Cheshire, backed Rory Stewart in the leadership campaign, before from the contest on Wednesday. She has been a strong opponent of a no-deal Brexit.
On Thursday, she shared the phone messages on Twitter, and said: "Barely is the ink dry on the results and the dark ops begin. This is from a male Conservative MP to me as I sat on the train home."
In a follow-up tweet, she added: "It's bad enough when you get it from complete strangers. Is it any wonder three female MPs left."
Anna Soubry, Sarah Wollaston and Heidi Allen to join Change UK, citing concerns over the "the hard-line anti-EU awkward squad" in the Conservative Party.
Meanwhile, members of the public replied with messages of support for Ms Sandbach, calling the messages "shocking" and "disgusting".
The government's chief whip, Julian Smith, called it "totally unacceptable" and pledged to investigate.
He also thanked Ms Sandbach for supporting the government's Brexit deal three times in Parliament.Skip Twitter post by @JulianSmithUK Report End of Twitter post by @JulianSmithUK
Leadership hopeful, Foreign Secretary Jeremy Hunt, also tweeted support for Ms Sandbach, writing: "This is so wrong! We have to come together as a party..."
Ms Sandbach told the Press Association she had made an official complaint to the chief whip "and will get it dealt with internally."
Mr Johnson and Mr Hunt in the final stage of the leadership contest, which will end in late July following a postal ballot of Conservative Party members.