WASHINGTON — House Democrats are zeroing in on a framework for their impeachment case against President Donald Trump that will center on a simple “abuse of power” narrative involving the president's actions regarding Ukraine, according to multiple people familiar with the deliberations.

As Democrats continue closed-door depositions with critical witnesses and prepare to move to the next phase of public hearings, they are wrestling over which elements and evidence to bring in, which to leave out. The goal is to explain to the public the reasoning and relevance of any eventual impeachment charges.

Democratic House committee chairs and leaders are still debating the need for additional articles or charges that extend beyond the president's dealings with Ukraine, but Speaker Nancy Pelosi has been adamant that the case against Trump must be targeted and easy to communicate in order to build public support, according to those familiar with discussions.

That’s especially true since Democrats are hoping to win the votes of at least some moderate House Republicans who will be asked to vote against a president who has demonstrated a willingness to unleash his vast campaign resources on party dissenters.

Neal Katyal, a former acting U.S. solicitor general and NBC News contributor, said that legally and politically, a sweeping impeachment article charging “abuse of power” with regard to Ukraine was "exactly correct.”

“The phrase captures the central evils of what Trump did in Ukraine," Katyal said, "and keeps the story focused there, and not on distracting sideshows.”

House aides stressed that no decisions have been made and that it is too early to discuss the specific legal framework before all of the evidence is collected.

But one person familiar with the strategy said “abuse of power” when it comes to Ukraine is the “big point that Pelosi has been hammering home” and the umbrella under which “this all fits to connect it and help the public understand.”

“What made it abusive is it was done in a way that betrayed the country and our national security interests and helped his own interests politically,” said another source involved in the discussions.

Pelosi is also considering a separate article on obstruction or contempt of Congress related to the administration’s blanket rejection of subpoena requests for documents and witnesses related to its inquiry into Trump’s efforts to pressure Ukraine to investigate former Vice President Joe Biden and his son Hunter, according to multiple sources involved in the deliberations.

House leaders learned the importance of a simple message after special counsel Robert Mueller’s report on Russian interference in the 2016 election was “exceptionally compelling but too hard to digest,” said Chuck Rosenberg, a former U.S. attorney and senior FBI official. “There seems to be a clear pattern of the president doing things for personal political gain” in Ukraine while putting “U.S. national security at risk,” he said.

“The abuse of power narrative is much simpler” to understand, said Rosenberg, who is also an NBC News contributor.

An Oct. 17 memo on impeachment messaging from Rep. Cheri Bustos, D-Ill., who leads the House Democrats’ 2020 election strategy, underlines the approach. The memo was sent to the entire House Democratic Caucus describing a poll that found broad national support for advancing the inquiry. Even in the 57 most competitive battleground districts, the internal polling found that 49 percent favor the inquiry moving forward.

In those same battlegrounds, 54 percent of respondents said it is either very or totally convincing that Trump is “abusing his authority” and that lawmakers need to “uphold the rule of law.” The findings are important given that Pelosi had been concerned about political fallout for her party’s most vulnerable Democrats of any impeachment inquiry. In the memo, Bustos says the “the numbers do not back up Republicans’ posture that impeachment worsens the political environment for House Democrats.”

Her first bullet point of messaging guidance to Democrats reflects the survey findings, noting that Trump “abused his power and put himself above the law.”

Trump and the White House deny any wrongdoing when it comes to their dealings with Ukraine and say the president was cleared of wrongdoing in the Mueller report.

In a news conference last week, House Intelligence Committee Chair Adam Schiff, D-Calif., said the next phase of the impeachment process will likely be open hearings where evidence is presented to the public and the full House.

That will include the most compelling testimony collected from witnesses, documents collected by House investigators and at times the president’s own words. The three committees overseeing the Ukraine investigation have issued 12 subpoenas for witnesses, many of them current or former diplomats and State Department officials.

The House Judiciary Committee, which historically has been given the task of drafting the legal language for articles of impeachment, has also added a constitutional law expert, Joshua Matz, to their staff.

The House investigation has resulted in a flood of new information in recent weeks, including evidence that suggests Trump pushed aside the U.S. ambassador to Ukraine, Marie Yovanovitch, so that a team of his political appointees — some calling themselves "the three amigos" — could pressure the Ukrainian government to create a corruption narrative, and possible charges, against the Bidens.

There has been no evidence of wrongdoing by either Biden.

Some evidence also suggests there was an effort to withhold a White House meeting sought by President Volodymyr Zelenskiy, as well as $391 million in aid Congress had appropriated to help Ukraine to defend itself against Russian aggression, unless Zelenskiy acquiesced to Trump's request to do him a “favor” by investigating an energy company linked to Hunter Biden.

In an Oct. 16 letter to the Democratic caucus, Schiff warned that defying subpoenas would be considered “evidence of the president’s effort to obstruct the impeachment inquiry, and we may also use that obstruction as additional evidence” of “the president’s underlying misconduct.”

White House Counsel Pat Cipollone wrote to Pelosi on Oct 8 that the administration would not cooperate at all with what he called the House’s “constitutionally invalid” impeachment inquiry. The White House has also attempted to block testimony by witnesses, including U.S. ambassador to the E.U. Gordon Sondland, actions that could be central to any obstruction or contempt of Congress article.

Still under debate is whether leaders will roll potential obstruction charges related to Mueller’s investigation into the same article that deals with Ukraine, the sources said. In the case of Ukraine, House Democrats consider the Cipollone letter strong evidence of an intent to obstruct. Whether any potential obstruction evidence related to Mueller’s report would be included remains undecided, given former White House counsel Don McGahn’s refusal to testify before Congress, the sources said.

Last week, House lawyers, in a court filing related to McGahn, accused Trump of trying to "obstruct his own impeachment."

Multiple congressional committees have been investigating additional possible charges against the president and his administration, including those related to profits earned overseas and at home as president in violation of the Constitution’s Emoluments Clause, among others. Judiciary Committee Chair Jerrold Nadler, D-N.Y., wrote to committee chairs in August asking them to send him their most important findings.

There is some tension in the caucus over whether the approach should include additional articles based on evidence collected, for instance, by the House Judiciary, Financial Services and Oversight Committees. Having multiple articles could give some vulnerable Democrats the political advantage of allowing them to vote in favor of the broader abuse of power charge while opposing others, said a lawmaker involved in the discussions.

Still, according to two sources close to the process, at this time, an additional article beyond obstruction and Ukraine is "highly unlikely.”

“Pelosi has been very focused on trying to make it airtight with whatever articles of impeachment are voted on and moving in the strongest possible way,” one lawmaker close to the process said.

In a recent interview on MSNBC’s “Morning Joe,” Pelosi said, “We have to stay focused as far as the public is concerned on the fact that the president of the United States used taxpayer dollars to shake down the leader of another country for his own political gain.”