Former special counsel Robert Mueller's report about wrongdoing in the 2016 election provides "very substantial evidence" that President Donald Trump is "guilty of high crimes and misdemeanors," an impeachable offense, says a key leader in the House of Representatives.

Rep. Jerry Nadler, D-N.Y., chairman of the House Judiciary Committee, told Fox News Sunday, "We have to...let Mueller present those facts to the American people, and then see where we go from there, because the administration must be held accountable and no president can be above the law." Nadler's committee would conduct official impeachment proceedings if House leaders decide to hold them.

Democrats, who control the House, are divided on whether to start formal impeachment proceedings. Last week, the House voted to kill an impeachment resolution but many Democrats considered that proposal premature and they hope the Mueller hearing will create new momentum for impeachment.

Nadler said, "If anyone else had been accused of what the report finds the president had done, they would have been indicted."

Mueller, a former FBI director, is scheduled to testify before Congress Wednesday about his report. Trump's fellow Republicans are expected to attempt to discredit any testimony implicating Trump and apparently plan to ask Mueller about the origins of the investigation and whether it was justified.

For nearly two years, Mueller led a Justice Department probe into Russian interference in the 2016 presidential election and possible collusion and obstruction of justice by the Trump campaign, Trump associates and Trump himself. Mueller's report, released in April, found no criminal collusion by Trump but took no position on whether Trump should be prosecuted for obstruction of justice. Mueller said in May that his investigation did not exonerate Trump for obstruction and added that charging the president for such offenses was forbidden by rules of the Justice Department, for which Mueller worked as special counsel.

"If we had had confidence that the President clearly did not commit a crime, we would have said so," Mueller said. "We did not, however, make a determination as to whether the President did commit a crime."

