WASHINGTON – A blocked number in Donald Trump Jr.’s phone records may be among the first targets for Democrats on the House Intelligence Committee in January as they investigate possible ties between the Trump campaign and Russia.

Rep. Adam Schiff, who is poised to lead the committee when Democrats take over the House majority, told USA TODAY his committee will have to prioritize the most important witnesses and records that Republicans blocked them from pursuing. The “clearest example” of that obstruction, he said, is phone records that would show whether the blocked phone number – logged as Trump Jr. arranged a meeting in 2016 with a Russian lawyer in Trump Tower – belonged to presidential candidate Donald Trump.

Trump’s son arranged the meeting in June 2016 after being promised “dirt” on Democratic nominee Hillary Clinton. At first, Trump Jr. said he never told his father of the meeting, then he told Senate investigators he couldn't recall whom he spoke with that night.

Schiff said the committee, under GOP Rep. Devin Nunes' leadership, refused to seek records that would unmask the blocked call, leaving a major question unanswered.

“Republicans refused to look at the phone records so that we could find out because they were afraid of what the answer might be,” the California Democrat said.

Democrats will revisit witnesses Republicans wouldn’t call, records they wouldn’t obtain and witnesses that showed up but refused to answer questions without any legal basis for doing so, Schiff said.

GOP Intelligence Committee spokesman Jack Langer said Schiff “doesn’t have the best track record in proving his various conspiracy theories – but good luck to him on his hot cellphone lead.”

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Republicans on the House Intelligence Committee ended their investigation of Russian interference in the 2016 presidential election in March, concluding there was “no evidence of collusion” with the Trump campaign. Democrats continued their investigation, but they didn’t have the power to subpoena witnesses or records while in the minority.

Come January, that will change. Schiff said Democrats will continue their work on the Russia investigation, looking for foreign influence in U.S. elections or on policymakers. He said it’s important to examine whether Russians laundered money for the Trump organization and whether Russians have financial leverage over Trump.

Republicans used their subpoena power “essentially as a way to supplement the president’s legal defense fund,” Schiff said. “Obviously that’s going to come to an end.”

Schiff, a former federal prosecutor, said in February that there was "ample evidence" that the Trump campaign colluded with Russia in 2016, though he left it up to special counsel Robert Mueller to try to prove it beyond a reasonable doubt.

In that investigation, prosecutors announced Monday that former Trump campaign chairman Paul Manafort lied repeatedly to the FBI, violating a plea agreement with Mueller that authorities hoped would benefit the Russia investigation.

Trump has called the investigation a "witch hunt," and Tuesday morning, he went on a Twitter tear, bashing "Mueller and his gang of Angry Dems."

Schiff was among leading Democrats who this month demanded the preservation of documents relevant to Mueller’s work and the forced resignation of Attorney General Jeff Sessions, who was replaced by interim Attorney General Matthew Whitaker.

Schiff said Whitaker’s appointment is unconstitutional because he wasn’t approved by the Senate. Schiff told CNN on Sunday that “we are going to bring Whitaker before the Congress” to determine whether his appointment was designed to obstruct justice. Whitaker has been openly critical of the Mueller investigation.

Other areas of focus for the committee will be the rise of authoritarianism around the world and Saudi Arabia’s role in the murder of Washington Post columnist Jamal Khashoggi.

Schiff said he’ll keep a close eye on any interactions between Trump and Russian President Vladimir Putin when they are in Buenos Aires, Argentina, for the annual G-20 Summit.

Schiff told USA TODAY that he will try to get Republicans to work with Democrats on the Russia inquiry, but he said he wasn’t prepared to answer whether he’d seek votes on any subpoenas the committee might issue.

“We can’t obviously force them to work with us,” he said. “They’ll have to make the decision for themselves whether they’re interested in finding out the truth or they’re interested in merely being extensions of (Trump attorney) Rudy Giuliani.”

Contributing: Christal Hayes