WASHINGTON – Republicans and Democrats waited anxiously for more details – which could come as soon as Monday – about potential charges in special counsel Robert Mueller's probe into Russia's interference in the presidential election and possible collusion with President Trump's associates.

Just two days after reports that a grand jury approved the first charges in the federal investigation, Trump appeared ready for the other shoe to drop, taking to Twitter on Sunday to denounce the investigation, Democrats and his election opponent, Hillary Clinton.

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"All of this 'Russia' talk right when the Republicans are making their big push for historic Tax Cuts & Reform. Is this coincidental? NOT!" the president tweeted.

The president said Republicans were angry that investigators were focusing on "phony Trump/Russia 'collusion,' which doesn't exist" – rather than the Clinton campaign's involvement in what he called a "Fake Dossier." (Trump is referring to the infamous, and still unverified, dossier that alleges ties between President Trump and Russia.)

The Democrats, he continued, "are using this terrible (and bad for our country) Witch Hunt for evil politics, but the R's are now fighting back like never before. There is so much GUILT by Democrats/Clinton, and now the facts are pouring out. DO SOMETHING!"

It was unclear if Trump was pleading with the Justice Department, congressional investigators, the media or his 41 million Twitter followers to take action.

Yet some Republican members of Congress insisted that Mueller should be given the time to make his case. "Too defensive!" Sen. Rob Portman, R-Ohio, said of Trump's statements regarding the Russia probe.

"We ought to instead focus on the outrage that the Russians meddled in our elections, not just this last election," Portman said on NBC's "Meet the Press" show. "We need to get to the bottom of it and we need to go where the facts lead us."

CNN first reported late Friday that at least one charge in the federal Russia probe could become public as soon as Monday – though it remains unclear who would be charged or with that. The network reported that charges were sealed under orders from a federal judge.

Among those who have been under investigation are former White House national security adviser Michael Flynn and former Trump campaign manager Paul Manafort, whose Virginia home was raided by the FBI in July.

Mueller has used grand juries in Virginia and Washington, D.C. to advance a wide-ranging inquiry into possible coordination between the Trump campaign and Moscow during the election. He took over the probe after Trump in May fired FBI Director James Comey, who started it in July 2016. Peter Carr, a spokesman for the special counsel's office, declined to comment on Friday.

New Jersey Gov. Chris Christie said any leaks from the special counsel's office regarding the grand jury could be a criminal violation.

“We’ve got to make sure that the grand jury process remains confidential, remains secret, so that the special counsel can work effectively,” Christie said on CNN's "State of the Union."

Rep. Trey Gowdy, R-S.C., chairman of the House Oversight and Government Reform Committee, agreed. “It is kind of ironic that the people in charge of investigating the law and executing the law would violate the law,” Gowdy said on "Fox News Sunday."

"Make no mistake, disclosing grand jury material is a violation of the law," he continued.

Mueller is also investigating possible obstruction of justice.

Trump has said the Russia investigation was on his mind when he made the decision to fire Comey, and the former FBI director has publicly testified that the president pressed him to drop the probe into Flynn. The former national security adviser was fired after misleading Vice President Pence about his contacts with Russian ambassador Sergey Kislyak before Trump took office.

Preet Bharara, the Manhattan federal prosecutor Trump fired in March, said on CNN that people should watch not only what Mueller does this week but how Trump responds.

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Sebastian Gorka, Trump's former adviser who left the White House in August, tweeted Friday that if Mueller's team "executes warrants this weekend he should stripped of his authority by @realDonaldTrump. Then HE should be investigated."

Yet Bharara said talk among conservatives that Mueller should be removed was just "noise and politics." The special counsel, he predicted, is "here to stay for a while.”

And Sen. Angus King, a Maine independent who caucuses with Democrats, said on CNN that Mueller's first charges will be "really just the beginning."

Republicans in Congress also appeared worried Sunday that Mueller's investigation could detract from their plans to cut taxes and advance the party's stalled agenda.

"We've got a short window of time to deliver on tax reform," Sen. Bob Corker, R-Tenn., a frequent critic of the president, said on CBS' "Face the Nation."

Any news this week on Trump-Russia indictments, Corker said, "obviously ... will take up some space."