WATCH: House Dem threatens to introduce impeachment resolution

The House Democratic lawmaker calling for President Trump's impeachment is threatening to introduce a resolution to start the process in Congress.

"I have reserved the right and continue to reserve the right to introduce a resolution of impeachment. ... I have not done that but I will do that if it is not done by others," Rep. Al Green (D-Texas) says in an interview with The Hill's Molly K. Hooper.

Citing President Trump's recent firing of former FBI Director James Comey, Green says Trump "acknowledged that he was doing it with the [Russia] investigation in mind."