Republican Justin Amash outlines his 6 reasons for impeaching Trump

Rep. Justin Amash (R-Mich.) outlined the six reasons why he supports President Trump's impeachment in a Twitter thread on Thursday, saying that the president pushed "a consistent effort ... to use his office to obstruct or otherwise corruptly impede [special counsel Robert Mueller's] investigation."

Why it matters: The Michigan congressman, the only Republican in Congress to support impeachment, isn't backing down from his controversial position — even as big donors, like the DeVos family, begin to pull their support.

Here are Amash's six reasons for impeaching Trump, which are focused entirely on the obstruction aspect of Mueller's investigation:

1. Trump asked then-FBI Director James Comey to stop investigating then-national security adviser Michael Flynn.
2. Trump asked then-Attorney General Jeff Sessions to un-recuse himself from the Russia investigation.
3. Trump asked then-White House counsel Don McGahn to have Mueller removed, stating it was necessary due to conflicts of interest.
4. Trump asked McGahn to state that the request to remove Mueller never happened, suggesting McGahn could be fired if that did not take place.
5. Trump asked his former campaign manager Corey Lewandowski to tell Sessions to limit the scope of Mueller's investigation.
6. Trump wielded his pardon power to influence associates facing prosecution from Mueller, like Michael Cohen and Paul Manafort, not to cooperate.

The bottom line, according to Amash: "The president has authority to fire federal officials, direct his subordinates, and grant pardons, but he cannot do so for corrupt purposes; otherwise, he would always be allowed to shut down any investigation into himself or his associates, which would put him above the law."

Go deeper: Democrats' new case for impeachment