"One thing I've learned about President Trump is that when you think he's at his most weakest point, that's when he goes hard," Johnson said in an interview Wednesday with CNBC's "Squawk Box."
While Johnson as a Democrat supported Hillary Clinton in the 2016 race, he was quick to say after the election that he would work with Trump for the betterment of the country. Johnson now supports Trump.
In Tuesday's voting, Democrats flipped enough seats to take the House majority from Republicans, NBC News projected. Republicans, however, are expected to keep control of the Senate and add seats.
When the new Congress is seated in January, Democrats will control the House for the first time since 2010, and House Minority Leader Nancy Pelosi is likely to return to the speakership.
Johnson has said he's known Trump for years. Johnson met with the then president-elect in 2016 and said at the time that he believes Trump wanted to work with African-Americans and all Americans to boost the economy.
In Wednesday's CNBC interview, Johnson said Trump will be able to work with Democrats on topics such as immigration, health care and drug pricing.
But he added such cooperation may be contingent on Democrats not seeking impeachment.
Looking at Trump's Twitter Wednesday morning, there are indications that Johnson is right on the money.
To any of the pundits or talking heads that do not give us proper credit for this great Midterm Election, just remember two words - FAKE NEWS