A Cambridge University professor has been dragged into the controversy over links between Donald Trump's presidential campaign and Russian Federation.
The president's outside lawyer, Rudy Giuliani, told NPR that Mueller's office has told the president's legal team that the part of the investigation involving the president-both the question of obstruction and collusion-would conclude by September 1 if the much-debated interview with Trump takes place by mid-July.
Giuliani told The Associated Press the aim was to wrap up the investigation ahead of the national midterm elections in October. "They said September, which is good for everyone, because no one wants this to drag into the midterms".
Former New York Mayor Rudolph Giuliani, now one of Trump's personal attorneys, nearly immediately undercut Trump's speculation about an informant.
"This would be the culmination of the investigation into the president", Giuliani said.
It is not certain if Trump will sit for an interview with Mueller, though the president has publicly said he would.
Mr Trump also continued to assail special counsel Robert Mueller's Russian Federation probe as a "Witch Hunt".
Deputy Attorney General Rod Rosenstein responded later in the day.
The Justice Department probe had begun in March at the request of Attorney General Jeff Sessions and congressional Republicans.
Citing individuals familiar with the matter, The New York Times reported on Friday the informant interacted with Trump campaign advisers George Papadopoulos and Carter Page. Some cable TV commentators have pointed to a March 25 report from TheDCNF about Stefan Halper, a University of Cambridge professor who was in contact with both Page and Papadopoulos.
Meanwhile, House Democrats stood by the Justice Department following the President's demand for an inquiry into the department's actions regarding the Trump campaign.
Last month Devin Nunes, the chairman of the House Intelligence Committee and a close supporter of Trump, demanded the Federal Bureau of Investigation and Justice Department provide his committee with classified information on the informant, raising worries that the infamously leaky panel would expose his or her identity.
Nunes said, "If any of that is true, if they ran a spy ring or informant ring and paying people within the Trump campaign - if any of that is true, that is an absolute red line". "Never mind that DOJ has warned that lives and alliances are at risk". The Justice Department has refused to provide them.
California Democratic Representative Ted Lieu said that Trump's demand could amount to obstruction of justice. Giuliani defended the president's actions. "I don't know for sure, nor does the president, if there really was one", he told CNN. "To me, there's not much of a difference between an informant's ongoing collection of information in a surreptitious way or a spy".
While Trump allies in Congress have demanded more information about the informant, law enforcement officials have refused, saying the source - not yet officially identified - could be in danger if named. Schiff and other committee Democrats were furious and argued that Republicans had not subpoenaed many witnessed they considered essential to the committee's work.
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Promoting a theory that is circulating, Trump quoted Fox Business anchor David Asman and tweeted Friday: "Apparently the DOJ put a Spy in the Trump Campaign".
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Lemire reported from NY.