WASHINGTON, Nov 7 (Reuters) - President Donald Trump ordered the US Justice Department on Saturday to look into Democrats for “threatening a lot of people” with impeachment and other ​forms of punishment, saying in a social media post that their actions amount ‌to a “criminal act,” without providing evidence.

Democratic candidates routed Trump’s Republicans in midterm elections on Tuesday, giving them control of Congress starting in January. Party leaders have promised to reassert Congress’ oversight of the executive branch once ​they are in power by holding hearings and conducting investigations into Trump administration actions.

In ​his post, Trump accused Democrats of sending “threatening letters to many people, all innocent.”

Members ⁠of Congress have released copies of letters seeking documents on matters such as tech company donations ​for the large ballroom Trump is building at the White House.

Trump’s post also referred to Democratic ​Senator Elissa Slotkin of Michigan, who suggested in remarks last month at the University of Chicago that Congress should investigate people who have enabled Trump’s policies.