WASHINGTON - A US congressional panel on Monday said it found no evidence that US President Donald Trump's campaign had colluded with Russia, giving him a rare victory in a prolonged probe that saw some of his associates charged.

"The House Intelligence Committee has, after 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," Trump tweeted Monday afternoon after the panel made the announcement.

Earlier in the day, the Republican-controlled House Intelligence Committee cited a 150-page draft report saying the Trump campaign has not sought Russia's help during the election, but has taken a few missteps.

"We've found no evidence of collusion," Representative Mike Conaway, who oversaw the drafting of the report, told reporters Monday.

"Perhaps some bad judgment, inappropriate meetings, inappropriate judgment at taking meetings" have happened, Conaway said, such as a June 2016 gathering at Trump Tower in New York City between members of the Trump campaign and a Russian lawyer, which "shouldn't have happened".

"We couldn't establish the same conclusion as the CIA (Central Intelligence Agency) did that they (Russia) specifically wanted to help Trump," Conaway said.

Notably absent from the drafting of the report were efforts from House Democrats, who have long alleged that collusion between the Trump campaign and Russia existed.

Conaway said the Democrats will be able to review the report and weigh in starting Tuesday, and the report will be released to the public in weeks.

The panel's lead Democrat Adam Schiff lambasted the report as a "tragic milestone" and a "capitulation to the executive branch," saying "Republicans will be held accountable for abandoning a critical investigation of such vital national importance."

"We have the evidence that we need now to come to the conclusion that we came to," Conaway said, adding that if compelling information surfaces down the line, he would consider reopening the probe.

The House Intelligence Committee has reviewed more than 300,000 documents and interviewed 73 witnesses since launching the investigation in January 2017.

The witnesses includes former White House chief strategist Stephen Bannon, the president's eldest son Donald Trump Jr. and Trump's son-in-law and senior adviser Jared Kushner.

As Trump has already announced his presidential bid for a second term, House Republicans were eager to close the case.

"After more than a year investigating Russia's actions in the 2016 election, we are well into the primary season for the 2018 elections, and experts are warning that we need to safeguard against further interference," said AshLee Strong, a spokeswoman for House Speaker Paul Ryan, adding "That's what this next phase is about, and we hope Democrats will join us in seeing this through."

The House investigation ran parallel to a probe by Robert Mueller, who was tasked by the Department of Justice to determine if the Trump campaign had colluded with Russia.

Mueller's office has been peeling off layers of Trump's campaign, bringing charges to a number of individuals who were members or associated with members of the campaign and interviewing more, including Trump's lawyers and close confidants.

The White House has acknowledged that it was in talks with Mueller's office regarding a possible interview with Trump, and pledged that Trump will fully cooperate with Mueller's probe.