'Nothing wrong with help from Russians': Trump's lawyer

US President Donald Trump's lawyer Rudy Giuliani insisted there was "nothing wrong" with the president's 2016 campaign taking information from the Russians, as House Democrats pledged to investigate campaign misconduct and possible crimes of obstruction detailed in special counsel Robert Mueller's report.

Giuliani called the Trump campaign's effort to get political help from representatives of the Russian government possibly ill-advised but not illegal.

"There's nothing wrong with taking information from Russians," Giuliani said Sunday, referring to a June 2016 Trump Tower meeting involving Trump's son Donald Jr., son-in-law Jared Kushner and former Trump campaign chairman Paul Manafort and a lawyer linked to Russia. The Trump campaign was seeking harmful information on Democratic presidential candidate Hillary Clinton.

The Sunday news shows offered the latest back and forth following the long-anticipated release on Thursday of Mueller's 448-page redacted report on his two-year investigation into Russian interference in the 2016 presidential election.

Mueller found no evidence of a conspiracy between Russia and the Trump campaign and made no decision on obstruction of justice.

Giuliani rebutted Senator Mitt Romney who said in a statement on Twitter Friday he was "sickened" by the findings in Mueller's report that cited details on how the Trump campaign welcomed political dirt from Russia.

He added that Romney should "stop the bull", saying that accepting negative information about a political opponent is common.

"I would have advised, just out of excess of caution, don't do it," he said. Nevertheless, "there's no crime."

Pressed about whether there is a something wrong about using information stolen by foreign adversaries, Giuliani said, "It depends on the stolen material."

Trump, who spent the holiday weekend at his private Mar-a-Lago club in Palm Beach, Florida, asserted in tweets Sunday that he had been fully cleared by Mueller's report and that Democrats' continued efforts to investigate him will prove politically costly.

"Despite No Collusion, No Obstruction, The Radical Left Democrats do not want to go on to Legislate for the good of the people, but only to Investigate and waste time. This is costing our Country greatly, and will cost the Dems big time in 2020!" he tweeted.

Mueller explicitly did not exonerate Trump in the report on the question of obstruction, citing in part Justice Department guidelines that a sitting president shouldn't be indicted.

Not ruling out impeachment, Representative Jerrold Nadler, who chairs the House committee that would hold impeachment hearings, said he remained puzzled why Mueller did not bring charges of criminal conspiracy against those in the Trump Tower meeting.

"All you have to prove for conspiracy is that they entered into a meeting of the minds to do something wrong and had one overt act. They entered into a meeting of the minds to attend a meeting to get stolen material on Hillary (Clinton). They went to the meeting. That's conspiracy right there," said Nadler.

Nadler said it was now up to Congress to investigate after the special counsel said it did not establish enough evidence to bring charges of criminal conspiracy, yet detailed ten allegations of Trump's attempts to obstruct the Russia investigation that left open whether Trump broke the law.

Asked whether the offences are impeachable, Nadler told NBC, "If proven, some of this would be impeachable, yes." He said Democrats' current focus is to "go where the evidence leads us."

Nadler has subpoenaed the Justice Department for the full, underrated report and said Sunday he was adding former White House counsel Don McGahn to the list of people he would call to testify before his committee, along with Mueller and Attorney General William Barr.

According to the special counsel's report, McGahn was among the Trump aides who effectively halted Trump's efforts to influence the Russia investigation, rebuffing his demand to set Mueller's firing in motion.

Nadler has said he expects the Justice Department to comply with the subpoena for the full report by 1 May, the same day Barr is to testify before a Senate committee and one day before he is to appear before Nadler's panel. Nadler summoned Mueller to testify by 23 May.

Democratic leaders are under mounting pressure from the party's rising stars and some 2020 presidential contenders, including Sen. Elizabeth Warren of Massachusetts and Julian Castro, a former Housing and Urban Development secretary, to start impeachment proceedings.

House Speaker Nancy Pelosi is pushing for a step-by-step approach to the House's oversight of Trump and has refused to consider impeachment without public support, including Republicans. Pelosi is convening House Democrats on Monday to assess next steps.

Senator Mike Lee, a member of the Judiciary Committee, said it would be a "mistake" for Democrats to pursue further investigations that could lead to impeachment proceedings, arguing that the American public won't stand for it after Mueller failed to conclude that crimes had been committed.