"I worry that allegations and speculations are getting ahead of the facts," Collins told MSNBC. "We have a lot of anonymous sources, we have a memo that no one has seen but it's been read from, and that's why we need special counsel to take care of criminal aspects."
On Wednesday night, Deputy Attorney General Rod J. Rosenstein appointed Mueller as special prosecutor to investigate Trump and his aides' alleged dealings with the Russian government before the 2016 presidential election.
The White House and Moscow have denied the accusations. Kremlin spokesman Dmitry Peskov has said Moscow did not have official contacts with Trump's team during the presidential campaign.