President Donald Trump decried Democrats' for claiming the nation is facing a constitutional crisis after the White House refused to comply with demands from Congress, which says it is trying to perform its oversight function

"The Democrats new and pathetically untrue sound bite is that we are in a “Constitutional Crisis," Trump tweeted Sunday night. "They and their partner, the Fake News Media, are all told to say this as loud and as often as possible. They are a sad JOKE!"

The president portrayed the use of the phrase as part of an effort to distract from his administration's successes.

On Sunday, Sen. Kamala Harris said the nation is witnessing a "breakdown of responsibilities" and that "we probably are" in a constitutional crisis as the White House

The 2020 Democratic presidential candidate said on CNN's "State of the Union" that a "constitutional crisis is generally when the system that we set up with checks and balances, when each of the independent co-equal branches of government, fails to perform its duties."

Harris joins other high-ranking Democrats, including House Speaker Nancy Pelosi, D-Calif., and House Judiciary Committee Chairman Jerry Nadler, D-N.Y., in describing the standoff between the executive and legislative branches as a crisis.

As a U.S. senator from California and member of the Senate Judiciary Committee, Harris said she has seen "up close where there is a failure to respect the significance of Congress' duty to perform a role of oversight." And she said she's seen "a failure to appreciate the importance of testifying before Congress in a way that is straightforward and truthful."

On Thursday, Harris sent a letter to Attorney General William Barr asking him to "clarify" or "supplement" his answers to her questions during his appearance before the Judiciary Committee about whether President Donald Trump had asked him to investigate his political opponents.

"I think we're seeing the breakdown of responsibilities," Harris said. "We saw it last week in the Barr hearing. We're seeing it in terms of a failure to comply with subpoenas."

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On Wednesday, Nadler's committee held Barr in contempt for refusing to provide an unredacted copy of special counsel Robert Mueller's report on Russian 2016 election interference. And that morning, President Donald Trump claimed executive privilege over the full report.

And the White House has fought a subpoena for former White House counsel Don McGahn, whom Nadler also threatened with contempt if he fails to appear before Congress by the end of the month.

Nadler said the administration's attempts to stonewall Congress puts the country in a "constitutional crisis", and on Thursday, Pelosi agreed.

Pelosi:America in a 'constitutional crisis' over Trump stonewalling

"We’re talking about a cumulative effect of obstruction that the administration is engaged in. And the president is declaring that he is not going to honor any subpoenas from the Congress," Pelosi told reporters.

House Intelligence Committee Chairman Adam Schiff, D-Calif., said on ABC's "This Week" that the Trump administration has "decided to say a blanket 'no'" to "any kind of oversight whatsoever" by "claiming executive privilege over things that it knows there is no basis for."

"They're just stonewalling," Schiff said Sunday. "They want to draw this out as long as possible and we're going to fight it."

Schiff said that "if the courts take too long" the House would "have to consider other remedies" such as fining members of the administration $25,000 a day "until they comply."

Pelosi has counseled Democrats to be cautious in calling for the "divisive" process of impeachment, but she has said Trump's refusal to cooperate with congressional oversight could leave it as their only option.

Rep. Seth Moulton – a Massachusetts Democrat who is also seeking the presidential nomination – said on "Fox News Sunday" that impeachment proceedings would give Congress a stronger legal argument to compel the administration's cooperation.

Trump and his supporters, including Senate Majority Leader Mitch McConnell, R-Ky., have said Mueller's report – which detailed a "sweeping" effort by the Russian government to sway the election for Trump, but did not find evidence of a conspiracy between the Trump campaign and the Kremlin – should be the end of the investigations into the president.

"Case closed," McConnell declared on the Senate floor last week.

But days later news broke that the Senate Intelligence Committee, chaired by Sen. Richard Burr, R-N.C., had issued a subpoena for Donald Trump Jr.

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And congressional Democrats argue that many questions remain from the Mueller report, particularly whether the president acted criminally in 10 instances where Mueller outlined acts that could constitute obstruction of justice.

House Minority Leader Kevin McCarthy, R-Calif., said Sunday on CBS' "Face the Nation" that "the country wants to move forward" and that neither the ongoing congressional investigations nor Trump Jr.'s testimony would "change the outcome of the Mueller report."

"The Democrats are more interested in subpoenas than solutions," he said.



McCarthy repeated Barr's argument that he cannot disclose the redacted portions of the Mueller report because of laws protecting grand jury information.

He said Nadler and other congressional leaders have been offered the chance to read "99.9%" of the Mueller report, referring to an offer from the Justice Department for 12 members of Congress to look at a less redacted version of the report. Democrats rejected the offer, demanding the full report be made available to the general public.

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Sen. Rand Paul, R-Ky., said Sunday on "This Week" that "since the very beginning," the entire Mueller investigation was "politically motivated." Paul agreed with Barr's assertion – which has been disputed by other legal experts – that the president could not be charged with obstruction if he was not guilty of an "underlying crime" to begin with.

Paul also agreed that the handling of the investigation raised constitutional questions, but he said the "primary constitutional issue here" is whether the Foreign Intelligence Surveillance Act was used to "spy on a presidential campaign."

Barr has said he believes "spying did occur" in the government's investigation of the Trump campaign and has promised a review of the investigation's origins.

Former FBI Director James Comey has rejected Barr's "spying" assertion and defended the investigation as the proper response to reports of contacts between the Trump campaign and Russians offering access to hacked emails that were purportedly damaging to Hillary Clinton.

"We have had a giant SCAM perpetrated upon our nation, a Witch Hunt, a Treasonous Hoax. That is the Constitutional Crisis & hopefully guilty people will pay!" Trump tweeted on Sunday.

Contributing: Eliza Collins, Rebecca Morin and Nicholas Wu