I’m a day or two late on this, otherwise I’d likely have just posted it as a comment, but here goes.
Democrats in Congress should introduce a non-binding resolution rejecting/condemning the notion that the January 6th attack on the capital, any violent attack on the capital — or any attack on the government or its officials — constitutes “legitimate political discourse.” Keep the language non-partisan — most, if not all, of us know who’s responsible, but keeping it neutral (“no one should be doing this” rather than “You stop doing this right now you horrible people”) is going to make it harder to spin.
Preface it with a suitable mixture of “We thought this went without saying, but here we are” and “@GOPChairwoman says that’s not what they were referring to, and we look forward to hearing their explanation and actual stance on the matter. Here’s ours.” Possibly with a side order of “We’ll leave the matter of determining who did what crimes to law enforcement and DoJ, but we want to be clear that violence and intimidation have no place in politics.”
Given the statement by the RNC, TFG’s rallys, and the general state of politics here, such a measure can hardly be called unnecessary. And given how uncontroversial a position it is, it should be a fairly quick vote even if it can’t be passed via unanimous consent (and honestly, I’d lean towards not trying for UC; make every last one of them go on record on this) — so bringing it up can hardly be taking up much time for congress (arguing/debating will, rather obviously, take up more time than proposing it could). So, that dispenses with the good faith or even can-pass-for-good-faith arguments against it. While some of them will still employ bad faith arguments about it, it’s not a winning fight for them.
So then put it to debate and vote. The House seems to be having an easier time going to vote with measures (not sure if that’s a difference in rules, or one of there being a larger margin there), which forces every Republican to go on record on whether they’re prepared to agree with this resolution (potentially offending their base) or if they’re openly embracing violence as a political tactic (at which point the campaign ads for this fall write themselves).
Over in the Senate, they can filibuster, but that arms the Democratic party with a “we can’t even get 10 Republicans to agree with us that political violence is bad” point to make continued demands that Democrats not do anything without Republican support that much less tenable. The only advantages filibustering gives them in this case that it's likely to garner less media attention, and allows senate Republicans who are up for re-election to have it both ways on how they would have voted.