Twitter told Sen. Kamala Harris that it would not suspend President Donald Trump‘s Twitter account in a letter sent to the Harris presidential campaign.

Harris has called for Twitter to ban Trump’s account and urged fellow candidate Sen. Elizabeth Warren to support her efforts during the Democratic debate Tuesday night.

“I would urge you to join me because here we have Donald Trump who has 65 million Twitter followers and is using that platform as the presidents of the United States to openly intimidate witnesses, to threaten witnesses, to obstruct justice and he and his account should be taken down,” Harris said to Warren.

She wrote to Twitter two weeks ago saying that Trump had used his account to “target, harass, and attempt to out the whistleblower,” whose complaint that the president had abused his power for political motives caused House democrats to open an impeachment inquiry.

“We understand the desire for our decisions to be ‘yes/no’ binaries but it not that simple,” wrote Vijaya Gadde of Twitter’s trust and safety teams in a letter to Harris. “We reviewed the Tweets you cite in your letter, and they do not violate our policies against abusive behavior, targeted harassment, or violence on the server.”

Harris’ Mational Press Secretary Ian Sams said in a statement given to CNN that “Twitter is not holding Donald Trump accountable for abusing their platform to threaten people and incite and inspire violent behavior.”

He continued, “As Donald Trump uses his tweets to incite violence, threaten witnesses and investigators, obstruct justice, and inspire mass shooters and pipe bombers, this response is inadequate. Twitter is admitting that their rules are a mess and that they have one set of standards for Donald Trump and another for the rest of us.”