Democrats in the US House of Representatives have published a resolution setting out the next steps in their impeachment efforts against President Donald Trump. The motion sets out a more public phase of the inquiry and hands the lead role in hearings to the chairman of the intelligence committee, Adam Schiff. The House, controlled by the Democrats, will vote on the measure on Thursday. A White House spokeswoman said the resolution was an "illegitimate sham". So far, hearings have been held behind closed doors. This vote to make the impeachment process public is about the procedure, and not a ballot on whether or not to impeach the president. Republicans have criticised Democrats for the closed hearings up to this point, in which Republican lawmakers have also taken part. But Democrats insist they were needed to gather evidence ahead of the public stage of the inquiry, and deny allegations they have been secretive. President Trump is accused of trying to pressure Ukraine into investigating unsubstantiated corruption claims against his political rival, Joe Biden, and his son who worked with Ukrainian gas company Burisma. Mr Trump denies wrongdoing and calls the impeachment inquiry a "witch hunt". On Tuesday, the impeachment inquiry heard from Lt Col Alexander Vindman, a White House official who had monitored a phone call on 25 July between Mr Trump and Ukrainian President Volodymyr Zelensky. That call sparked a whistleblower complaint and led to the impeachment probe. Col Vindman said he was "concerned" by the call as he "did not think it was proper to demand that a foreign government investigate a US citizen". Some details of the call were omitted from the official transcript, despite his attempts to have them included, Col Vindman added, according to US media citing sources.