When Speaker Nancy Pelosi announced on Thursday that House Democrats would proceed with articles of impeachment, she did so in the language of duty, history, and the Constitution. “This has nothing to do with politics,” she said. “It’s about the Constitution of the United States.”

In almost the same breath, Pelosi revealed that it does, in fact, have at least something to do with politics. Asked what her “a-ha” moment was—the thing that got the long-reluctant speaker on board with impeachment—she said the Ukraine allegations against President Trump “changed everything.”

“The polls,” said Pelosi, “went from 59 percent opposed to impeachment, to 34 in favor, to now even.”

That conspicuous juxtaposition of lofty principle and hard political reality highlights the tension at the heart of the impeachment process as it heads into a decisive stretch. This week, Democrats’ sense of obligation and their sense of politics will be on a collision course as lawmakers debate, draft, and introduce their articles of impeachment against Trump, which are set to be revealed within days.

That’s because the decision of what, exactly, to impeach Trump over will challenge the near-unanimity that’s existed within this big, fractious group of Democrats. Their overwhelming consensus so far has been that the president’s desire to pressure Ukraine into doing him personal political favors merited the use of the House’s most powerful check against a president for just the fourth time in the country’s history.

No such consensus existed for other elements of Trump’s conduct in office, particularly the allegations of obstruction of justice outlined in Special Counsel Robert Mueller’s report. The majority of the public, as Pelosi noted, did not feel those charges justified impeachment—and neither did she. Even though over half of the Democratic caucus was publicly supportive of impeachment before the Ukraine story emerged, the moderate and purple-district lawmakers who won them the majority dismissed a Mueller-based impeachment drive as political suicide.

Now, Democratic leadership and lawmakers on the House Judiciary Committee—the panel that led House Democrats’ charge on all things Mueller—are weighing whether to weave that thread into articles of impeachment. Few on Capitol Hill predict this will be a fight that tears the party apart, but strong views on the subject abide, and lawmakers on both ends of the debate are anxiously bracing for a decision that amounts to something like a final judgment from House Democrats on the president’s conduct.

“From the very beginning, we were clear that the process should be clear, strategic, and efficient,” said Rep. Elissa Slotkin, a freshman Democrat from a Trump-won district in Michigan. In a September op-ed written with several like-minded colleagues, Slotkin called for an impeachment inquiry based squarely on the anonymous whistleblower’s complaint. The move went down as the speaker’s come-to-Jesus moment on impeachment; she launched the inquiry the next day.

“Clear, meaning we have to make the case to the American people. We got that strategic focus on specific articles, hone in on those—don't take a kitchen-sink approach, really think strategically. And then efficient. This doesn't need to be an 18-month process,” Slotkin told The Daily Beast on Thursday. “I have made myself clear that it should be a very tight group of articles, very limited, very focused.”

This view is not exactly shared by many of Slotkin’s colleagues. “You might say I’m in the kitchen sink caucus,” said Rep. Jared Huffman, a northern California Democrat who has long backed impeachment.

“This office has been abused and damaged in profound ways,” Huffman said on Friday. “I personally would be for holding him accountable for every bit of it. Not for every grievance we have—I wouldn't include his bad behavior or his offensive rhetoric—but some specific actions that I believe that have abused authority and rise to the level of impeachable offense, in my view, would go well beyond the current Ukraine scandal.”

But many Democrats in this boat admit the moment is simply too important for the party to suffer any real show of discord. Huffman says he would “accept a more strategically focused set of articles if that's the decision,” but said he expected some kind of compromise to emerge.

Over the weekend, the Judiciary Committee, led by Chairman Jerry Nadler (D-NY) held closed-door discussions about the possible scope of articles of impeachment and prepared members of the panel for the significant week to come. On Monday, the committee will convene for a hearing where lawmakers will hear prepared evidence for impeachment.

According to a source familiar with the committee’s plans, Democrats spent the weekend huddling with Harvard constitutional law professor Lawrence Tribe and holding mock hearings—during which Democrats played the roles of GOP members like top Judiciary Republican Rep. Doug Collins (R-GA), who has made parliamentary and process based interruptions central to the party’s hearing strategy.

The format of the hearing is a sign that Mueller’s Russia investigation could get another high-profile public airing. On Monday, attorneys for both Judiciary and the House Intelligence Committees will present evidence that Trump committed impeachable offenses. Intelligence submitted a lengthy report on the Ukraine matter, but Judiciary has spent all year focused on Mueller.

On Sunday, Nadler appeared on CNN and said that he is seriously considering an article of impeachment based on the Mueller findings in order to establish a “pattern” of wrongdoing by Trump that goes beyond Ukraine and encompasses his entire presidency.

Democrats both on Nadler’s panel and around the caucus see the logic to that move. “If there is an obstruction article, how do you ignore documented evidence of obstruction by the special counsel, for which he essentially said, ‘I’m not charging because of the Justice Department policy regarding the charging of a president,’ the Congress has remedies available,” said Rep. Dan Kildee (D-MI) on Friday. “To me, that's just like, a great big blinking light that says, yeah, you really need to look at that.”

An idea percolating within the caucus is that the Mueller-related charges could be put to the floor precisely so that moderates could vote against them, while the Ukraine-focused articles would stand a far stronger chance of passing. “Including one or two counts of obstruction for the Mueller report is totally appropriate,” said Huffman. “And if our more politically fragile members feel like they've got to vote against that, let them do it.”

But among those who represent competitive districts, taking such a vote may not be such an appealing prospect. One aide associated with the moderate wing of the party said any vote on Mueller-focused impeachment grounds puts these lawmakers in a “terrible position.”

“Largely, there’s no support of idea of bringing up articles about Mueller,” said the aide, calling the investigation’s entire subject matter politically “toxic” in the districts these lawmakers represent. This wing of the party is anxiously watching to see how Nadler—likely with a heavy hand from the speaker—draws up the articles. “Thirty-one Democratic members of Congress in Trump districts are going to be living with the decisions he makes for the next year,” said the aide.

There’s some hope, however, that this could result in some kind of compromise to be brokered this week that reconciles the tension baked into Democrats’ impeachment enterprise. “I mean, we're not gonna send everybody home happy,” said Huffman. “That's just inherent in the situation that has been forced upon us.”

Among some of the lawmakers who decided to support impeachment knowing it could be a liability back home, there’s a sense that the most important Rubicon has already been crossed.

“For many of us, if this was purely a political issue, we would not have come out in support of an inquiry,” said Slotkin, who is just one of several Democrats already seeing hundreds of thousands of dollars worth of impeachment-based attack ads against them in their districts.

“So you have this threshold where you say, doesn't matter what a poll says, it doesn't matter what my consultants are telling me to do, what matters is right and wrong.”