"What we really need to look at right now are the conflicts of interest," Bernstein told David Axelrod on "The Axe Files," a podcast from the University of Chicago Institute of Politics and CNN, remarking on the opacity of Trump's vast international business holdings.
One place to begin digging, Bernstein proposes, is around Trump's attempted dealings in Russia and the surrounding region. Additional scrutiny should be given there, he argues, in light of Trump's welcoming gestures to President Vladimir Putin and his timidity to support the US intelligence community's assessment that the Russians interfered with the US presidential election.
"We have no idea what Trump's businesses, associations, loans are in greater Russia," he said. "This is a big job for investigative reporting. It's a big job for Republicans in Congress, especially because it's going to come back to bite them."
Bernstein, a Pulitzer Prize winner, is also a contributing editor with CNN¹s new Investigative Unit.
He offers several key questions journalists must seek to answer in order to gain a better understanding of the President's business dealings in Eurasia.
"What do you own? How much did you pay for it? Who are your business partners? Whom do you owe? How much do you owe?"
"That's all we want to know," Bernstein added. "And put it out there. We need to know all of your holdings -- not just in greater Russia, but greater Russia especially."
The conversation with Bernstein took place on the day before Trump's inauguration.
Since then, a senior Trump official confirmed that the President will not release his personal tax returns -- documents that likely would provide needed clarity on his finances. Additionally, while Trump has removed himself from the day-to-day business operations of his company, he still stands to profit from its dealings and therefore, say ethics experts of both parties, has not adequately neutralized those potential conflicts.
Bernstein, whose investigative reporting at The Washington Post helped uncover the Watergate scandal that led to the resignation of President Richard Nixon, suggests Trump is stonewalling so the public cannot learn of the "unsavory" business practices that helped make him a success.
"There is an established record that (Trump's) success is based on a con and on treating people badly and suing people and not meeting his obligations that he agreed to," he said.
Bernstein also noted that the same Republican Party that assailed Democrat Hillary Clinton for alleged conflicts of interest is now turning a blind eye to Trump's potential exposure.
"If Hillary Clinton had been the President of the United States and had the conflicts of interest -- patent, obvious conflicts of interest -- that Donald Trump has, there would be already a congressional investigation and it would lead to something horrible," Bernstein maintained.
Indeed, it was reported this week that Rep. Jason Chaffetz, the chairman of the House Oversight and Government Reform Committee, has 43 proposed agenda items for possible investigation in the new Congress -- but nothing involving Trump's business dealings.
Chaffetz, however, suggested to CNN that no investigatory matter has been ruled out.
To hear the whole conversation with Bernstein, which also covered the details of the landmark reporting he did that exposed the Watergate cover-up and led to Nixon's resignation, how he grappled with the forces of celebrity after he became a cultural figure, and much more, click on http://podcast.cnn.com
. To get "The Axe Files" podcast every week, subscribe at http://itunes.com/theaxefiles.