( CNN) Most Americans continue to believe that the Russian effort to influence the 2016 presidential election is a serious matter that should be investigated, but the constant criticism by President Donald Trump of special advise Robert Mueller is taking its toll, according to a CNN poll conducted by SSRS released Friday.

And look how Giuliani's public image has really taken a reach. Once upon a day, America's Mayor was viewed favorably by two-thirds of all Americans. As recently as 2011, a majority still had a positive position of him. In 2016, his favorable rating was 19 phases higher than his unfavorables. Now 45% have an unfavorable position of Giuliani and merely 31% ensure him in a positive sun.

Negative positions of Mueller don't mean that the public is taking Trump's side. Just 29% approve of how Trump is handling the Russia investigation. Merely 35% say it is an attempt to discredit Trump's presidency. Nearly 7-in-10 believe Trump should witness under oath if Mueller requests it. Another 70% would disapprove if Trump issues himself a presidential forgivenes, with no majority in any demographic group. Trump has said he perfectly has the power to pardon himself but doesn't need to.