WASHINGTON (ABC News) – The impeachment inquiry into President Donald Trump and his Ukraine call enters a new phase with public hearings for several key witnesses set for this week.

The first public hearing will prominently feature members of the House Intelligence Committee who have spent weeks grilling witnesses from across the Trump administration behind closed doors.

The first hearing of the House intelligence committee’s hearing is scheduled for 8 a.m. on Wednesday, with the second on Friday at 9 a.m.

Democrats aim to focus public attention on what they argue was President Donald Trump’s inappropriate push to pressure Ukraine’s president to investigate the Biden family and 2016 election, and efforts to make nearly $400 million in military aid to Ukraine contingent on the probes.

For their part, Republicans on the committee, including some of Trump’s staunchest defenders, have argued that Trump’s actions were not inappropriate and within his rights as a president conducting foreign policy, while raising questions about the testimony of several witnesses and their knowledge of the president’s frame of mind during the events at the center of the inquiry.