WASHINGTON — After two years and 200 interviews, the Senate Intelligence Committee is approaching the end of its investigation into the 2016 election, having uncovered no direct evidence of a conspiracy between the Trump campaign and Russia, according to both Democrats and Republicans on the committee.

But investigators disagree along party lines when it comes to the implications of a pattern of contacts they have documented between Trump associates and Russians — contacts that occurred before, during and after Russian intelligence operatives were seeking to help Donald Trump by leaking hacked Democratic emails and attacking his opponent, Hillary Clinton, on social media.

"If we write a report based upon the facts that we have, then we don't have anything that would suggest there was collusion by the Trump campaign and Russia," said Sen. Richard Burr, R-N.C., the chairman of the Senate Intelligence Committee, in an interview with CBS News last week.

Burr was careful to note that more facts may yet be uncovered, but he also made clear that the investigation was nearing an end.

"We know we're getting to the bottom of the barrel because there're not new questions that we're searching for answers to," Burr said.

On Tuesday, Burr doubled down, telling NBC News, "There is no factual evidence of collusion between the Trump campaign and Russia."

Sen. Mark Warner, D.-Va., ranking member of the committee, told reporters in the Capitol Tuesday that he disagrees with the way Burr characterized the evidence about collusion, but he declined to offer his own assessment.

"I'm not going to get into any conclusions I have," he said, before adding that "there's never been a campaign in American history ... that people affiliated with the campaign had as many ties with Russia as the Trump campaign did."

Democratic Senate investigators who spoke to NBC News on condition of anonymity did not dispute Burr's characterizations, but said they lacked context.

"We were never going to find a contract signed in blood saying, 'Hey Vlad, we're going to collude,'" one Democratic aide said.

The series of contacts between Trump's associates, his campaign officials, his children and various Russians suggest a campaign willing to accept help from a foreign adversary, the Democrats say.

By many counts, Trump and his associates had more than 100 contacts with Russians before the January 2017 presidential inauguration.

"Donald Trump Jr. made clear in his messages that he was willing to accept help from the Russians," one Democratic Senate investigator said. "Trump publicly urged the Russians to find Clinton's missing emails."

Those facts are beyond dispute. But they also have been known for some time — and have not seemed to change Trump's political standing.

Democrats and other Trump opponents have long believed that special counsel Robert Mueller and Congressional investigators would unearth new and more explosive evidence of Trump campaign coordination with Russians. Mueller may yet do so, although Justice Department and Congressional sources say they believe that he, too, is close to wrapping up his investigation.

House Republicans announced last year they had found no evidence of collusion, but their report came under immediate criticism as a highly partisan product that excluded Democrats. Now in power, House Democrats recently announced an expanded probe that will go beyond the 2016 election to examine whether any foreign government has undue financial influence on Trump or his family. And New York federal prosecutors are pursuing their own criminal inquiry related to hush-money payments to women. The investigations into Donald Trump, therefore, are far from over.

The Senate Intelligence Committee has been conducting the sole bipartisan inquiry. The committee has sifted through some 300,000 documents, investigators tell NBC News, including classified intelligence shedding light on how the Russians communicated about their covert operation to interfere in the 2016 election.

U.S. intelligence agencies assess that the operation began as an effort to sow chaos and morphed into a plan to help Trump win. It included the hacking and leaking of embarrassing Democratic emails and the use of bots, trolls and fake accounts on social media to boost Trump, criticize Democrat Hillary Clinton and exacerbate political differences.

Predictably, Burr's comments led Trump to tweet that he had been fully vindicated, which is not the case.

"Senator Richard Burr, The Chairman of the Senate Intelligence Committee, just announced that after almost two years, more than two hundred interviews, and thousands of documents, they have found NO COLLUSION BETWEEN TRUMP AND RUSSIA!" Trump tweeted Sunday. "Is anybody really surprised by this?"

Democratic Senate investigators say it may take them six or seven months to write their final report once they are done with witness interviews. They say they have uncovered facts yet to be made public, and that they hope to make Americans more fully aware of the extent to which the Russians manipulated the U.S. presidential election with the help of some Trump officials, witting or unwitting.

View this graphic on nbcnews.com

The report, Democrats say, will not be good for Trump.

But they also made clear they haven't found proof of their worst fear: That the president formed a corrupt pact with Russia to offer sanctions relief or other favorable treatment in return for Russian help in the election.

After it recently emerged in court documents that Trump campaign chairman Paul Manafort shared campaign polling data with a man the FBI says is linked to Russian intelligence, Warner called that the most persuasive evidence yet of coordination.

"This appears as the closest we've seen yet to real, live, actual collusion," he said on CNN.

No evidence has emerged, however, linking the transfer of polling data to Trump. Also unclear in court documents is Manafort's motive for sharing the information. Facing more than a decade in prison for bank and tax fraud, he has not been accused by Mueller of any crimes related to the 2016 election.

Burr, in the CBS interview, said the motivations behind the Trump campaign's interactions with Russians were in some cases impossible to discern.

"There's an awful lot of connections of all these people," he said. "They may not be connections that are tied to 2016 elections in the United States, but just the sheer fact that they have a relationship — it may be business. It may be Russian intelligence. It may be they're all on the payroll of Oleg Deripaska," he added, referring to a Russian oligarch tied to Putin who had business dealings with Manafort.

The final Senate report may not reach a conclusion on whether the contacts added up to collusion or coordination with Russia, Burr said.

Democrats told NBC News that's a distinct possibility.

"What I'm telling you is that I'm going to present, as best we can, the facts to you and to the American people," Burr told CBS. "And you'll have to draw your own conclusion as to whether you think that, by whatever definition, that's collusion."