Of the 46-and-counting House Democrats who think Congress should open impeachment proceedings, only one is from a Republican-leaning district - Rep. Tom Malinowski of New Jersey. Most of the rest represent heavily liberal communities, places like Portland, Oregon, or some of the most liberal neighborhoods in New York City.
Pelosi's primary job is to keep the House of Representatives in Democratic control, and she's not worried about winning these districts again in 2020. She's worried about lawmakers in tight races in swing or even moderately Democratic districts, the people you don't see on this list. Given that polls show a majority of Americans oppose impeachment of Trump - even if most think the president lied - most of those lawmakers are staying quiet.
Most members of Congress who support impeachment have nothing to lose in doing so. In fact, you could argue that lawmakers such as Reps. Adriano Espaillat, D-N.Y., or Barbara Lee (Calif.) would lose credit back home if they didn't call for Trump's impeachment. They represent some of the most anti-Trump places in the country.
Espaillat's Manhattan district voted for Hillary Clinton in 2016 over Trump by a margin of 87 percentage points. The nonpartisan Cook Political Report, which assigns each congressional district a partisan ranking based on how Democratic- or Republican-leaning it is, ranks his district as Democratic by 43 points! (For comparison, an average swing district leans one way or the other by three points or less.)
Another ultraliberal lawmaker firmly in the impeachment camp is Maxine Waters, D-Calif. She chairs the House Financial Services Committee, and she was one of the first members of Congress to call for impeaching Trump, well before the Mueller report was released. She represents a heavily Hispanic part of Los Angeles that voted for Clinton by a margin of 61 points.
And as such, Waters can say things like this about Trump on her Twitter account:
"Low life Trump - lying, crooked, tax evader, porn star fornicator - should take his ridiculous self home, resign, and free us of what we will have to do to impeach him and throw him out of office!"
Pelosi isn't worried about these lawmakers. The ones she is focused on live in much more conservative places in Georgia, like newly elected Rep. Lucy McBath, or Iowa, like Rep. Abby Finkenauer. Both represent districts that voted for Trump in 2016, and both knocked off Republicans last year to win their seats. They are top Republican targets for 2020.
On Thursday afternoon, Rep. Greg Stanton, D-Ariz., announced he supported impeachment proceedings. He represents a Democratic-leaning district, but it's not quite as liberal as the others on this list. And he spent considerable time in his statement acknowledging his decision might be unpopular with some of his constituents.
"This is a conclusion I reached only recently," he said, "and not one I reached lightly."
By virtue of winning back control of the House in 2018, Democrats have quite a few vulnerable newly elected lawmakers. The Cook Political Report ranks 17 Democratic-held seats as toss-up races, compared to just four Republican-held ones.
More centrist Democrats than liberals picked up Republican-held seats, points out Jim Kessler, a Democratic strategist with the centrist think tank Third Way. Their reelections will be critical for helping House Democrats keep their majority in 2020, and thus their concerns arguably carry more weight than the ones liberals have.
That's especially true when it comes to impeachment.
There's an argument the pro-impeachers make that opening impeachment proceedings against Trump is the right thing to do for the history books. Special counsel Robert Mueller made a rare public statement this week in which he made it clear that it is up to Congress to act if it wants to, given that he was hamstrung by Justice Department guidelines that bar charging a president with a federal crime while he is in office.
Hundreds of former federal prosecutors from Democratic and Republican administrations think Trump would have been charged with a crime if he were not a sitting president.
Another pro-impeachment argument being made behind closed doors to Pelosi maintains that saying the "i" word will actually help House Democrats win court battles with Trump over information for their investigations.
The courts are more likely to force the Trump administration to hand over documents and testimony and the unredacted Mueller report if Congress needs them to carry out its constitutionally mandated right to impeach a president.
But the moral and practical reasons for impeachment - however valid they may be - don't stand up to Pelosi's political concerns that impeachment would jeopardize her hard-won majority.
And until public opinion on impeachment moves in such a way that these vulnerable lawmakers feel OK supporting it, the growing list of Democrats who are calling for impeachment will remain on the liberal side of the aisle, and they won't have much sway on Pelosi.