House Intelligence Committee Chairman Adam Schiff Adam Bennett SchiffSchiff to subpoena top DHS official, alleges whistleblower deposition is being stonewalled Schiff claims DHS is blocking whistleblower's access to records before testimony GOP lawmakers distance themselves from Trump comments on transfer of power MORE (D-Calif.) said on Sunday obstruction of Congress may be the "most serious of the articles" of impeachment against President Trump Donald John TrumpBiden says voters should choose who nominates Supreme Court justice Trump, Biden will not shake hands at first debate due to COVID-19 Pelosi: Trump Supreme Court pick 'threatens' Affordable Care Act MORE.

"Why is going to court an impeachable offense?" Wallace asked, referring to Trump's efforts to block administration officials from aiding in the inquiry.

Schiff responded that "going to court is not an impeachable offense" but "stonewalling completely, refusing to comply with the oversight of Congress, particularly during an impeachment inquiry" is.

TODAY: Adam Schiff defends the two Articles of Impeachment put out by House Dems and the reasoning behind them. #FNS #FoxNews #ArticlesofImpeachment pic.twitter.com/sgiMZuJPcq — FoxNewsSunday (@FoxNewsSunday) December 15, 2019

He cautioned that if the Republican party is "prepared to say a president of the US can simply say no to any Congressional subpoena and tie up Congress for years in litigation, it is going to have to accept corruption, malfeasance, negligence, misconduct, in any future president, Democrat or Republican."

"In many respects, I think this is the most serious of the articles because it would fundamentally alter the balance of power and allow for much greater misconduct in the chief executive of the country," he said.

Schiff also defended House Democrats' decision to charge the president with abuse of power, rather than bribery or another more specific charge that had been discussed. Trump and his allies have attacked Schiff and other Democrats for what they see as "weak charges."

"We charged the president with abusing his power. Bribery and extortion are a subset of abuse of power," Schiff said. "And frankly abuse of power better connotes the full range of the president's misconduct, the pattern of his misconduct."

The House is expected to vote this week on the articles of impeachment, which passed the chamber's Judiciary Committee in a party-line vote last week. The Senate -- where Republicans hold a majority -- would then decide whether to remove Trump from office.