Trump had been widely expected to fire Sessions after Tuesday's midterm elections. "He has called the Mueller probe a "lynch mob" and publicly described how he would strangle the investigation", Anna Galland, executive director of MoveOn Civic Action, one of the organizers of the protests, told Sputnik News.
Asked Wednesday if Whitaker would take control of the probe, Justice Department spokeswoman Sarah Flores said Whitaker would be "in charge of all matters under the purview of the Department of Justice".
"Sessions did not do the thing he could have done to better protect Rosenstein, and through Rosenstein, the Mueller investigation", Vladeck said.
Sessions' ouster "just makes us all the more want to make sure we have that special counsel protection bill passed or added to any spending bill that may be moving in the (end-of-year) session", said Representative Mark Pocan.
Trump named Matthew Whitaker, a public critic of the investigation, as acting attorney general, prompting an outcry from Democrats and a handful of Senate Republicans who fear Whitaker will try to interfere with the probe.
Watchdog group Citizens for Responsibility in Washington called on Whitaker to recuse himself from overseeing the Russian Federation probe. He has previously said that he saw no basis for firing Mueller.
In fact, Whitaker told CNN past year that a future attorney general could limit Mueller by reducing the budget "so low that his investigations grinds to nearly a halt". "Deputy Attorney General Rosenstein must be allowed to protect the Special Counsel and insulate the investigation from interference by the White House".
After starting his career in private practice, Whitaker first ran for office in 2002, losing a race for state treasurer to longtime Democratic incumbent Michael Fitzgerald.
New York City Rep. Jerrold Nadler - who is now the ranking Democratic member of the House Judiciary Committee and could be the next chairman of the committee with Democrats taking control of the U.S. House of Representatives - questioned the president's move on Twitter and said that "we will be holding people accountable".
Former U.S. Attorney General Alberto Gonzales said he's "profoundly concerned" that the new acting attorney general is someone who has criticized and publicly expressed skepticism about the Russian Federation investigation.
He also announced media leak crackdowns and tougher policies against opioids, and his Justice Department defended a since-abandoned administration policy that resulted in migrant parents being separated from their children at the border.
Despite demands from Democrats and ethics watchdogs that he recuse because of his past comments, Whitaker showed no signs Thursday that he meant to do so. The almost year and a half long investigation by the special counsel stems from allegations of Russian Federation coordinating with members of the Trump presidential campaign.
The short-list came after George Conway III, a prominent lawyer, penned an op-ed in the New York Times along with former solicitor general Neal Katyal, arguing that Trump's power play at the Justice Department is 'unconstitutional'.
As reason for his recusal, Sessions cited news reports of two undisclosed meetings he had with Sergey Kislyak, then Russia's ambassador to Washington. "I'd like to know the truth", said Pat Noga, an Emmaus resident.