President Trump has refused to release his tax returns, saying that he is being audited. Experts have said that an audit would not prevent him from releasing his returns. (Jabin Botsford/The Washington Post)

President Trump claimed Thursday that congressional Democrats are subjecting him to the “highest level of Presidential Harassment” in the nation’s history.

His grievance, aired on Twitter, comes amid a push by House Democrats to obtain six years of Trump’s personal and business tax returns as well as the full report of special counsel Robert S. Mueller III into Russian interference in the 2016 presidential election.

Trump has previously said he has no objection to making the full Mueller report public, but he has seemed less committed to that aim amid reports that members of Mueller’s team think the findings are more damaging to him than suggested in a four-page summary released by Attorney General William P. Barr.

“There is nothing we can ever give to the Democrats that will make them happy,” Trump wrote on Twitter. “This is the highest level of Presidential Harassment in the history of our Country!”

Democrats are certain to take issue with that assessment, given the impeachment of President Bill Clinton by the Republican-led House in 1998.

In a separate tweet, Trump said that “few people seem to care” about the Russia investigation and complained that some Democrats are “fighting hard to keep the Witch Hunt alive.”

“They should focus on legislation or, even better, an investigation of how the ridiculous Collusion Delusion got started - so illegal!” Trump wrote.

The House Judiciary Committee voted along party lines Wednesday to subpoena the Mueller report and underlying documents from Barr.

In a previous letter to Congress, Barr said the special counsel did not establish a criminal conspiracy between the Trump campaign and Russia. And he said that Mueller did not reach a conclusion “one way or the other” as to whether Trump’s conduct in office constituted obstruction of justice.

Absent such a determination, Barr told lawmakers that he concluded the evidence was not sufficient to prove that the president obstructed justice.

The New York Times and Washington Post reported Wednesday that members of Mueller’s team have complained to close associates that the evidence they gathered on obstruction was alarming and significant.

White House spokesman Hogan Gidley denied Thursday that Trump’s views on releasing the Mueller report have changed.

“The president wants it public, just like Congress wants it public, consistent with the law,” he told reporters. “You have to protect sources and methods. What he was trying to articulate, which he did, is that no matter what we do — we could release the entire thing from top to bottom — it’s never going to be enough for Democrats. . . . He wants it to be public. He wants people to understand what he went through.”

Trump was quick to suggest Wednesday that he is not inclined to cooperate with an effort by the House Ways and Means Committee to secure his tax returns, which Democrats think can shed light on numerous aspects of Trump’s business dealings.

The committee gave the Internal Revenue Service until April 10 to respond to its request for the returns. The panel’s chairman, Rep. Richard E. Neal (D-Mass.), was able to make the request because of a 1924 law that gives the chairmen of the House Ways and Means Committee and the Senate Finance Committee broad powers to request and receive the tax returns of any American.

Trump broke with precedent when, first as a presidential candidate and then after he was elected, he refused to release his tax returns, contrary to the practice of every president since Richard M. Nixon. The explanation he gave was that he was being audited, although numerous experts have said that an audit would not have prevented him from releasing his returns.

At an event at the White House on Wednesday after Neal issued his request, Trump repeated the same explanation.

“We are under audit, despite what people said, and working that out — I’m always under audit, it seems, but I’ve been under audit for many years because the numbers are big, and I guess when you have a name, you’re audited,” Trump said. “But until such time as I’m not under audit, I would not be inclined to do it.”

During an appearance Thursday morning on Fox News’s “Fox & Friends,” White House spokeswoman Sarah Sanders pointed to Trump’s remarks Wednesday when asked whether he intends to let his returns become public.

Sanders said that Democrats’ continuing scrutiny of Trump shows they are “sore losers” and “a sad excuse for a political party.”

Ellen Nakashima and Erica Werner contributed to this report.