During a commencement address at Liberty University on Saturday, a somewhat subdued President Trump reflected on a tumultuous past week prompted by his abrupt firing of FBI Director James B. Comey amid a federal investigation of possible ties between Trump’s 2016 campaign and Russians seeking to influence the outcome.

Trump said that he has shown “courage” and “guts” in shaking up the established order in Washington – even as he has touched off a political firestorm on Capitol Hill over dismissing Comey and stoked a constitutional debate over whether he was intentionally obstructing a federal investigation that some argue could eventually lead to his impeachment.

Related: Trump Admits He Made Decision to Fire FBI Director Prior to DOJ Recommendation

“Nothing worth doing ever, ever, ever came easy,” he told the graduates at the prominent evangelical Christian university in Lynchburg, Va. “It’s called the road less traveled.”

It’s hard to predict where this fast-moving political drama will lead: Trump has blatantly contradicted Vice President Pence and other senior White House surrogates’ explanations of why Comey as fired. In the process, Trump has left the clear impression that his major concern was that the FBI probe was picking up steam.

The president also made a veiled threat in a tweet against Comey to be careful about what he says about conversations the two men had prior to the dismissal. Comey reportedly may testify soon in open session before the Senate Intelligence Committee to give his side of the story. And Trump as repeatedly dismissed the FBI and congressional investigations into Russian involvement in the election as a “hoax” and waste of taxpayer money.

But Senate Minority Leader Chuck Schumer (D-NY), one of the most influential Democrats in the country, made it clear on Sunday that Trump’s “less traveled road” will either lead to the appointment of a special independent prosecutor to take over the FBI investigation or trigger an historic paralysis of legislative action – including the president’s selection of a replacement for Comey.

Related: The Inside Story on Why Trump Decided to Fire Comey

Appearing Sunday on CNN’s State of the Union and NBC’s Meet the Press, Schumer reiterated a Democratic call on Friday for the Department of Justice’s Inspector General to investigate the possibility of “political interference with the FBI’s investigation” into possible collaboration between Trump campaign aides and Russian officials to influence the outcome of the election in Trump’s favor.

And for the first time, Schumer strongly embraced a proposal by Sen. Mark Warner of Virginia, the Democratic vice chair of the Senate Intelligence Committee, which is also investigating the Russian campaign connection, to try to block the confirmation of a permanent replacement for Comey until the Justice Department agrees to appoint a special prosecutor to oversee the FBI investigation going forward.

“We need someone who is independent of the Justice Department to get to the bottom of this,” Schumer said on Meet the Press.

The New York Democrat said that while the Senate Intelligence Committee and other congressional panels are providing valuable oversight and review of the FBI probe, they lack the authority to indict or prosecute in the event criminal conduct is revealed. Some senators, including Republican Ben Sasse of Nebraska and Democrat Sheldon Whitehouse of Rhode Island, have warned that appointing a special prosecutor at this point might slow down the congressional investigation or undermine confidence its work.

Related: Special Prosecutor? Independent Counsel? Special Counsel? What’s the Difference?

“They can’t prosecute,” Schumer said of the congressional investigations in the Senate and House. “A special prosecutor appointed by the Justice Department has the ability to actually prosecute people for violations of law. And they [the congressional and FBI probes] go on in tandem. One shouldn’t step on the other . . . but it’s too separate issues, and we very much need a special prosecutor.”

Under the US Code, the Attorney General may appoint an outside Special Counsel “when he or she determines that criminal investigation of a person or matter is warranted and that investigation or prosecution of that person or matter by a United States Attorney's Office or litigating Division of the Department of Justice would present a conflict of interest for the Department or other extraordinary circumstances.”

Attorney General Jeff Sessions, a former Alabama senator and senior adviser to Trump’s campaign, recused himself from the investigation after it was revealed that he falsely testified during his Senate confirmation hearings in March that he had no contact with Russians during the campaign. In fact, he had two meetings last summer and fall with the Russian ambassador to the United States, Sergei Kislyak.

Related: Demands for a Special Counsel to Investigate Trump’s Russia Ties Just Got Louder

Last week, the White House revealed that Sessions and Deputy Attorney General Rod J. Rosenstein had urged Trump to fire Comey, largely for his questionable decision-making in the probe of former Secretary of State Hillary Clinton’s mishandling of government emails. And Sessions took part in the vetting of eight candidates to replace Comey, a decision that could be made as early as this week and will have a profound impact on the future direction of the Russian probe.

Senate Majority Leader McConnell has dismissed calls for an independent investigator to take charge of the investigation of Russian interference in the election as partisan and said the Senate would continue with its own investigation headed by Sens. Richard Burr (R-NC) and Warner.

Schumer acknowledged today that the current Senate rules requiring only a simple majority of the 100-member body to confirm Trump’s nomination of a replacement for Comey would make it impossible to block the president’s choice of a new FBI director unless several Republicans side with the Democrats. A new NBC News/Wall Street Journal poll found that just 29 percent of Americans approve of Trump’s decision to fire Comey.

“The key here, of course, is getting some of our Republican colleagues to join us,” Schumer said. “We’re hoping, we’re waiting, we understand it’s difficult. But I think patriotism and the needs of this country demand it.”