WASHINGTON (AP) — House Speaker Nancy Pelosi has introduced a new concept into the debate over President Donald Trump's actions: "self-impeaching."

As Trump all but goads Democrats into impeachment proceedings , viewing the showdown as potentially valuable for his 2020 re-election campaign , Democrats are trying to show restraint. Their investigations are both intensifying but also moving slowly as Democrats dig into the special counsel's Trump-Russia report and examine Trump's finances and governance.

The more they push, the more Trump resists, the president making what Pelosi says is his own case for impeachment with his stonewalling of Congress.

"The president is self-impeaching," she told her colleagues last week during a private caucus meeting, echoing comments she also aired in public. "He's putting out the case against himself. Obstruction, obstruction, obstruction. Ignoring subpoenas and the rest."

She added, "He's doing our work for us, in a certain respect."

There is no actual process for self-impeachment. It's a thought bubble more than a legal term. A pure Pelosi-ism, one that an aide says she coined herself.

But as a device, it's a way for Pelosi to frame the often complicated idea of the White House refusing to engage with Congress in the traditional process of checks and balances.

"Sometimes people act as if it's impeachment or nothing," Pelosi told reporters. "No, it's not that. It's a path that is producing results and gathering information."

In the aftermath of special counsel Robert Mueller's investigation, the slow drip of congressional oversight also serves a dual purpose politically. It allows Democrats to keep impeachment proceedings at bay, despite calls to push ahead by the liberal flank, while stoking questions about Trump going into the 2020 presidential election.

They note the Watergate investigation dragged on two years before the House Judiciary Committee opened impeachment proceedings against President Richard Nixon. By the time articles of impeachment were drawn up, the third entry was Nixon's obstruction of Congress.

Rather than viewing Mueller's report as the end of the debate, Democrats in Congress have taken his findings as a green light to dig in with their oversight role.

So far, House committees have issued multiple subpoenas for executive branch information, including for an unredacted version of the Mueller report and some million of pages of underlying evidence; for testimony and documents from former White House counsel Don McGahn; for information on Trump's business dealings; and for Trump's tax returns.

Others subpoenas have been issued over the administration's policies on migrant children and on citizenship questions on the census.

"My Democratic colleagues seem to be publicly working through the five stages of grief," Senate Majority Leader Mitch McConnell mused in a floor speech. The Kentucky Republican scoffed at their "laughable threats of impeachment."

As McConnell declared the "case closed," he noted that the final stage of grief is acceptance. "For the country's sake, I hope my Democratic friends get there soon," he said.

Except Mueller's 448-page report left Congress with questions. While the special counsel found no evidence the Trump campaign colluded with Russia to swing the 2016 election, Mueller did not render a decision on the question of whether the president obstructed justice in the investigation. "It also does not exonerate him," the report says.

At least one Republican, Sen. Richard Burr of North Carolina, chairman of the Senate Intelligence Committee, appears to have questions, too. His committee issued a subpoena for testimony from one of the president's sons, Donald Trump, Jr. The move sparked fierce blowback among allies of the White House and divided Senate Republicans into two camps: those who backed his oversight role and those who panned it.

Trump, during remarks at the White House, said he was "very surprised."

What his supporters want to know, the president said, is how the whole question of Russian interference first started. A top Trump ally in Congress, Sen. Lindsey Graham, R-S.C., is starting his own investigation into the investigation, picking up where House Republicans, when they controlled the committees before the lost he majority last year, left off.

House Democrats want Mueller to testify. His report notes that Congress has the ability to "apply the obstruction laws" as part of "our constitutional system of checks and balances and the principle that no person is above the law." The Democrats want Mueller to more fully explain what he found and what, if anything, he intended for them to do about it.

"Our strategy right now is just to get to the truth and the facts," said Rep. Jamie Raskin, D-Md., a member of the House Judiciary Committee.

Raskin said he kept a little chart on his notepad during a hearing last week, when the committee voted to hold Attorney General William Barr in contempt of Congress for refusing to turn over the full Mueller report, and it was the Republicans who most mentioned impeachment.

"The Republicans would love us to begin impeachment process," he said. "If we get to impeachment, we're going to get there on our own schedule and for our own reasons, not because they need to throw some red meat to their base."