Pressure is mounting for a transparent investigation into alleged ties between President Donald Trump's campaign and Russian intelligence, following a New York Times report that shows officials on both sides were in contact before the 2016 election.

The Times reported Tuesday that current and former American officials say Trump's associates and campaign staff, including then-chairman Paul Manafort, had "repeated contacts" with senior Russian intelligence officials in the year before the election. The officials cited phone records and other intercepted data.

American intelligence agencies began investigating potential ties between the teams after discovering evidence that Russia was attempting to hack into the Democratic National Committee (DNC), according to the sources.

However, the Times continues, "[t]he officials interviewed in recent weeks said that, so far, they had seen no evidence of such cooperation."

Indeed, CNN added in its own reporting, "Investigators have not reached a judgment on the intent of those conversations," and "cautioned the Russians could have been exaggerating their access."

The conflicting information—and reporting based on intelligence leaks—has bolstered the growing call for an independent probe as the only viable solution to the allegations, particularly as they come after Trump's national security adviser, Michael Flynn, abruptly stepped down on Monday amid reports that he had misled the White House about his communications with the Russian ambassador to the United States.

California Sen. Kamala Harris (D) tweeted that "Americans deserve a transparent, independent investigation into Russia's involvement with the Trump camp."

Her campaign website also includes a petition demanding the same, reading, "This administration owes the American people a public, transparent, bipartisan fact-based investigation into Michael Flynn's involvement with Russia and Russia's involvement in the 2016 election...We need to know the truth."

Highlighting the detail that the intelligence officials have not yet found evidence of collusion between the teams, The Intercept's Glenn Greenwald wrote, "Seems like an important caveat in an article treated as a smoking gun. Also: shows why this should be resolved w/investigation, not [intelligence community] leaks."

He added that people can "cogently believe" that both the Trump presidency and the intelligence community's "abuse of spy powers to subvert" the elected government are dangerous.

Indeed, the call for an independent probe or special prosecutor has grown so wide that leading Republicans have joined in, with Sen. Roy Blunt of Missouri, a member of the Senate Intelligence Committee, on Tuesday calling for an exhaustive investigation into the possible connections.

"I think everybody needs that investigation to happen," Blunt said on KTRS radio. "And the Senate Intelligence Committee, again that I serve on, has been given the principle responsibility to look into this, and I think that we should look into it exhaustively so that at the end of this process, nobody wonders whether there was a stone left unturned, and shouldn't reach conclusions before you have the information that you need to have to make those conclusions."

Advocacy groups have also raised the alarm.

"Voters deserve an impartial investigation of Russian interference in the 2016 presidential race by a Bipartisan Select Committee," said Common Cause president Karen Hobert Flynn on Tuesday. Although some separate Senate panels are planning their own hearings, "this scattered and competing approach... is not the best way to seek the truth."

"[T]hat can only be accomplished by a joint-, bi-partisan, Select Committee that should be convened immediately," she said.

Ilya Sheyman, executive director of MoveOn.org Political Action, added, "The question is whether Republicans in Congress are more interested in tax cuts for the wealthy than they are in finding out the truth and defending American security and interests. Nothing less than the safety of our nation depends on the answer to this question."