A Republican lawmaker has dismissed Trump-Russia collusion claims as a fictional "spy thriller", as his committee cleared the president.
House Intelligence Committee Republicans said they had found no evidence Mr Trump or his aides plotted with Russians to win the 2016 election.
But Democrats on the panel were furious, arguing the investigation had been prematurely ended.
The Senate Intelligence Committee is still probing the matter.
An investigation by Justice Department Special Counsel Robert Mueller is also ongoing.
What did House Republicans say?
Mike Conaway, the Texas Republican who has led the yearlong probe, announced on Monday that the House of Representatives committee had finished interviewing witnesses and planned to share a 150-page draft report with Democratic colleagues on Tuesday.
"We found no evidence that the Trump campaign or anyone associated with it colluded with the Russians," he said.
Mr Conaway said the worst the panel had found was "perhaps some bad judgment, inappropriate meetings, inappropriate judgment at taking meetings".
This appeared to refer to a June 2016 meeting between Trump campaign officials and a Russian lawyer at Trump Tower.
"But only [thriller authors] Tom Clancy or Vince Flynn or someone else like that could take this series of inadvertent contacts with each other, or meetings or whatever, and weave that into sort of a fiction page turner, spy thriller," Mr Conaway said.
He told reporters the inquiry agreed that Moscow had interfered in the 2016 US election, but rejected the conclusion of most American intelligence agencies that the Kremlin had aimed to help Mr Trump win.
"The bottom line: the Russians did commit active measures against our election in '16, and we think they will do that in the future," Mr Conaway said.
He added: "We disagree with the narrative that they were trying to help Trump."
The draft report includes 25 recommendations for Congress relating to election and cyber-security.
Mr Conaway said the panel had spoken to 73 witnesses and reviewed more than 300,000 pages of documents.
What did the president say?
The Republican president, who denies wrongdoing, pounced on Monday's statement by Mr Conaway, with a tweet all in capital letters.
THE HOUSE INTELLIGENCE COMMITTEE HAS, AFTER A 14 MONTH LONG IN-DEPTH INVESTIGATION, FOUND NO EVIDENCE OF COLLUSION OR COORDINATION BETWEEN THE TRUMP CAMPAIGN AND RUSSIA TO INFLUENCE THE 2016 PRESIDENTIAL ELECTION.— Donald J. Trump (@realDonaldTrump) March 13, 2018
What did House Democrats say?
Adam Schiff, the top Democrat on the committee, called the investigation "fundamentally incomplete" and accused Republicans of capitulating to Mr Trump.
"The [Republican] majority has placed the interests of protecting the President over protecting the country, and history will judge its actions harshly," he said.
The California representative said there were dozens more witnesses the panel needed to interview or subpoena for testimony.
"We have learned a great deal about countless secret meetings, conversations and communications between Trump campaign officials and the Russians, all of which the Trump administration initially denied," he said.
"If the Russians do have leverage over the president of the United States, the majority has simply decided it would rather not know."
Democrats on the panel are expected to release their own report.
The committee's inquiry has been embroiled in partisan rancour. Democratic members accused Republican colleagues of seeking to sabotage Mr Mueller's investigation, while Republicans charged Democrats with plotting to smear the president.
Political warfare rages on
Analysis by Anthony Zurcher, BBC News
The House Intelligence Committee's investigation has been mired in partisan bickering nearly from the start. The inquiry may be drawing to a close, but the political warfare is just getting started.
Did the committee do enough to look into possible Trump campaign ties to Russian election meddling? Were there other people investigators should have spoken with or documents they should have requested?
That these are the key questions is good news for the Trump administration - an admission that no clear-cut evidence of "collusion" has been unearthed. "We just didn't look hard enough" doesn't carry as venomous a political sting.
Expect Donald Trump to regularly cite the coming full report from the committee's Republican majority as exoneration, particularly its controversial conclusion that Russian efforts to disrupt the 2016 election were not specifically aimed at helping Mr Trump.
Of course, the House Intelligence Committee doesn't have the final say in this matter. There are benefits to being first to the post, however, and the House's conclusions could be used to undermine future reports - from the Senate and independent counsel Robert Mueller.
In a nation riven by political factions, that may be enough - even in the face of any future evidence - for Mr Trump's supporters to stick by their man.
What did Russia say?
The Russian embassy in the US praised Mr Conaway's findings.
The diplomatic mission posted apparently sarcastic tweets on Monday night with the hashtag "#JackRyan", a fictional character in author Tom Clancy's spy novels.
All “Russia investigations” (not only in the US) are destined to end as @ConawayTX11 brilliantly concluded: “only Tom Clancy could take this series of inadvertent contacts, meetings, whatever, and weave that into some sort of a spy thriller that could go out there”#JackRyan pic.twitter.com/rX4QEP7R3p— Russia in USA 🇷🇺 (@RusEmbUSA) March 13, 2018
The embassy also posted a photo of what it said was an American helicopter flying overhead and shining a spotlight on their compound.
The tweet included a UFO emoji and a mocking reference to the Trump-Russia investigation.
What was American helicopter searching for at the Russian Embassy's premises yesterday night? "Strange" malfunction of navigation equipment in the center of the US🇺🇸 capital? Or another desperate attempt to find traces of #RussianMeddling🛸? pic.twitter.com/LHUhYjKz5K— Russia in USA 🇷🇺 (@RusEmbUSA) March 13, 2018