Sample headline: "Moderate Democrats Back Impeachment of Trump as House Vote Nears"
Tag line from that particular version of the story: "Several vulnerable freshmen who had expressed reservations about the effort said they would vote to impeach President Trump, despite the political risks."
The story itself could probably be reversed, at least to a degree. That is, vulnerable Republican members of Congress will vote against impeachment despite the political risks.
The key word being "vulnerable." These politicians are in, pardon my French, a shit sandwich.
They're in seats where they're either vulnerable to being primaried if they don't toe their parties' lines (possibly with the assistance of their parties' national committees, etc.), or they're from "swing" districts where the "wrong" vote could put that district in the other parties' columns, or both.
My impression -- and it could be incorrect, I haven't dug into the statistics -- is that Republican members of Congress are more vulnerable to the former problem, Democrats to the latter.
That is, more Republican members of Congress are from districts where the party machine will just replace them with loyalists if they stray, while more Democratic members of Congress are from districts with large numbers of "blue dog" voters who will vote Republican if the Democrat isn't "moderate" (read, from that side of the aisle, "conservative") enough rather than "yellow dog" voters who would vote Democrat even if the party ran a yellow dog. And as we saw in 2018, the DNC will support "moderate" incumbents over "progressive" primary challengers six days a week and twice on Sunday.
Is there an opportunity here for Libertarian candidates next year? I think there might be, in terms of targeting incumbents of either "major" party who vote against the articles of impeachment (or, in the Senate, to acquit).
The attack "from the right" on Republican incumbents who don't support impeachment: The GOP has replaced any pretense of being ideologically "libertarian-leaning" with an open, unabashed loyalty test to a single individual -- an authoritarian president.
The attack "from the left" on Democratic incumbents who don't support impeachment: A Democrat who can't even be relied upon to support removing an authoritarian Republican president from office might as well be, well, a Republican.
On both sides, it helps that there's not an iota of doubt as to this particular president's guilt of the acts of which he stands accused. Impeachment may be a political process, but that doesn't mean voters will easily forgive treating it as a matter of threadbare political calculation.