WASHINGTON — The top Democrat on the House Intelligence Committee said he fears the panel's Russia investigation could end up producing two separate, partisan reports offering contradictory conclusions to Americans.

Rep. Adam Schiff, D-Calif., said he will work with other committee members "to do everything we can to prevent two separate reports" on Russian interference in the 2016 presidential election and possible collusion between the Trump campaign and Russian officials.

"The ideal would be a comprehensive report with bipartisan support," Schiff said in a phone interview from California with USA TODAY.

However, he noted that past investigations by congressional committees have often resulted in separate findings by Republicans and Democrats.

"It may still have to happen with us," Schiff said. "If it does, then Americans will have to read both reports and decide which one to believe. And that is far less than ideal."

Schiff said the committee still has a long way to go in its Russia investigation and he is hopeful that it can avoid a partisan split.

He said the panel has been "making progress" but that it's hard to say when the probe will be finished. The congressman expressed doubt that the investigation, which was announced in late January, would be completed this year.

"I think it would be difficult to conclude an investigation of this magnitude in a matter of months," Schiff said.

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Asked whether he thinks the committee has sufficient resources for its investigation, Schiff replied: "No, I don't."

"We ought to have two to three times the resources devoted to it," he said.

Schiff said those resources would have been greater if the House and Senate Intelligence committees had agreed to a joint investigation, combining their staff and funds. Republican leaders in the House and Senate would not agree to a joint probe, he said.

Although the two panels coordinate, they are conducting separate, often duplicative, investigations, Schiff said. He said the two committees are roughly in the same place in their respective probes.

Schiff praised the House panel's staff but noted that they are experts in analyzing the performance of intelligence agencies — which the panel oversees — and are not prosecutors, Schiff said.

For that reason, the Department of Justice investigation led by special counsel Robert Mueller and his team of prosecutors is better-equipped to deal with any criminal matters that arise from the probe, Schiff said. He said Mueller also has greater manpower.

"We're doing everything within the constraints of our resources to get the job done," Schiff said.

Schiff said he and Rep. Mike Conaway, R-Texas, who is leading the investigation for the Republican majority, plan to have public hearings in the weeks ahead, although nothing specific has been scheduled yet.

"I don't know that people should expect more of the kind of blockbuster witnesses that we've had in the past," Schiff said. Instead, the committee will be hearing publicly from outside experts rather than key figures in the investigation, he said.

Past witnesses at public hearings have included former CIA director John Brennan, former Homeland Security secretary Jeh Johnson, National Security Agency Director Mike Rogers, and former FBI director James Comey before Comey was fired by President Trump.

The committee is continuing to conduct closed-door interviews of key witnesses and reviewing scores of documents, Schiff said.

"There's a lot more I think we want to learn about why the Russians decided this was the time to interfere in our election," he said. "And of course, most importantly of all, we want to learn how we can prevent it from happening again."

In addition to Russia investigations by Mueller and by the House and Senate Intelligence committees, the Senate Judiciary Committee is conducting an inquiry.

Judiciary Chairman Chuck Grassley, R-Iowa, said at a recent town hall meeting in Iowa that he will ask committee members to vote on whether transcripts should be made public of a closed hearing with Glenn Simpson, the co-founder of the company that commissioned an infamous dossier on Trump.

Simpson was questioned on Aug. 22 by committee investigators about the dossier, which was commissioned by his opposition research firm, Fusion GPS. It was compiled by former British spy Christopher Steele.

The dossier, published online by BuzzFeed in January, alleged that Russian operatives obtained potentially compromising personal and financial information about Trump. The Russian government has denied having any "compromising materials" on Trump, who has dismissed the reports as “fake news.”

Congress is currently adjourned for its August recess, so committee members will vote sometime after they return on Sept. 5 about whether to make Simpson's testimony public.

Meanwhile, the Senate Intelligence Committee staff has been reviewing tens of thousands of documents and continuing to interview key witnesses while lawmakers have been on recess.

Chuck Johnson, a pro-Trump opposition researcher and editor of GotNews.com, revealed on Facebook that investigators from the Senate panel have asked to interview him and told him to preserve documents related to any communication with Russians involving the presidential election.

Johnson, who was reportedly banned from Twitter two years ago for threatening a "Black Lives Matter" activist, has vowed publicly not to cooperate with the committee's investigation.