GOP senator: Trump has changed presidency 'not necessarily toward the positive'

Johnson added that former President Clinton had also shifted the "behavior and the standard of the presidency."
"It's unfortunate. I revere our Constitution. I revere these institutions, including the office of the presidency. It would be nice if everybody conducted themselves, I guess, the way we would here in Wisconsin," Johnson continued. 
Johnson was asked about Trump's behavior, but didn't point to a specific incident during the interview. His comments come as Congress is locked in an impeachment fight fueled by the president's interactions with the leader of Ukraine.
Johnson, who has emerged as one of Trump's most vocal supporters on Ukraine, said on Monday that "there has been a concerted effort from Day 1 to sabotage this administration." 
"I don't agree with everything he's doing, but I have to give him a great deal of credit," Johnson said. 
The White House last week released a partial transcript of Trump's call with Ukrainian President Volodymyr Zelensky. In the call, according to the document, Trump asked Zelensky to work with his personal attorney Rudy GiulianiRudy GiulianiGreitens Senate bid creates headache for GOP Gaetz hires legal counsel amid DOJ probe Georgia lieutenant governor: Giuliani election claims helped lead to new voting law MORE, and expressed hope that he “can look into” former Vice President Joe BidenJoe BidenFour members of Sikh community among victims in Indianapolis shooting Overnight Health: NIH reverses Trump's ban on fetal tissue research | Biden investing .7B to fight virus variants | CDC panel to meet again Friday on J&J On The Money: Moderates' 0B infrastructure bill is a tough sell with Democrats | Justice Dept. sues Trump ally Roger Stone for unpaid taxes MORE and his son.
Johnson said on Monday that there was no "quid pro quo" in the Trump call, but that he has "a lot of questions" about Ukraine and Democrats. 
"Everybody says well there's no evidence, all these things have been debunked. ... [But] I have all kinds of questions dating back to Hillary ClintonHillary Diane Rodham ClintonPelosi on power in DC: 'You have to seize it' Cuba readies for life without Castro Chelsea Clinton: Pics of Trump getting vaccinated would help him 'claim credit' MORE's email scandal," Johnson said. 
Johnson has also called for an investigation into Biden, including suggesting that a Senate investigation would be "completely appropriate."