This is not because the news media has lost its traditional appetite for juicy tales of internal party conflict. Rather, it accurately reflects the unusually high level of Democratic unity on the impeachment issue. Importantly, this unity appears to endure even in private—unlike on the Republican side, where public displays of support for the president have been accompanied by multiple accounts of anonymous congressional dissatisfaction and sniping at the White House.
Much of the credit for keeping Democrats unified belongs to the Trump administration, combined with the parade of witness testimony that continues to reveal damaging facts about the Ukraine matter at a near-daily frequency. The White House can use the levers of partisanship and conservative media pressure to keep most Republicans from publicly breaking with the president, but it has no obvious strategy for, or even seemingly much interest in, persuading any Democrats not to go ahead and vote for impeachment and conviction. The red meat contained in the October 8 letter to Congress from White House counsel Pat Cipollone, for example, was (among other things) a signal that no Democrat who continued to harbor qualms about impeaching Trump was going to be provided with any defense of the president's position that did not primarily rely on appeals to partisan loyalty.
Still, party unity seldom happens without party actors maneuvering to encourage it. The impeachment process has so far been a showcase for the political acumen of House Speaker Nancy Pelosi, who has managed to keep both Trump-phobic liberals and risk-averse moderates on board with minimal defection or even complaint. Despite initial expectations that impeachment might cause a serious rift in the House Democratic Party, only two Democrats voted against authorizing formal impeachment inquiry procedures on Thursday. The Democratic leadership managed to win support from 29 of the 31 House Democrats representing congressional districts carried by Trump in 2016, including 8 of the 9 Democrats from seats where Trump outpolled Hillary Clinton by at least 10 percentage points.
Successfully wrangling moderate votes on the floor was only one way that the passage of the impeachment inquiry resolution demonstrated Pelosi's skill as a party leader. Though media coverage of the issue has been dominated by partisan fights over whether the House needed to formally authorize an inquiry and whether minority Republicans were being given enough procedural power, much of the resolution itself resolves what could have been a messy conflict over the roles played by relevant House committees as the drive toward impeachment begins to accelerate. Importantly, it places the House Intelligence Committee chaired by Adam Schiff at the center of the process—even though the Judiciary Committee has historically taken the lead in impeachment cases.
It's interesting to speculate about the reasoning behind this decision; my political science colleague Sarah Binder suggests that Pelosi might have given Intelligence the starring role in order to appease party moderates. (While the Intelligence Committee's former reputation for bipartisanship has broken down over the past few years, its membership is still less dominated by partisan show horses than the Judiciary Committee, long a haven for diehards on both sides.) There have also been media reports that Pelosi trusts Schiff more to preside over public hearings than Judiciary chairman Jerry Nadler, with whom she has supposedly lost confidence. In any event, turf wars in Congress can be brutal, and even more so when an opportunity arises for potential media stardom once the proceedings move into view of the cameras. So while the formalization of committee roles may seem like inside baseball compared to other aspects of impeachment, the speaker's resolution of this particular issue is a quiet but important illustration of her effectiveness.
Pelosi's success is not unblemished; she has notably failed, at least so far, at fulfilling her own stated belief that impeachment should proceed with bipartisan support (not counting the ex-Republican Justin Amash of Michigan, now an anti-Trump independent). But she continues to be a somewhat underrated figure in the legislative politics of the 21st century, even though her record compares favorably to most of the other leaders who have held the speakership over the past several decades. It's likely that retrospective historical analyses will recognize her key role in clearing the path toward what now looks like a near-certain presidential impeachment.