It's from Politico, so it should be taken with the proverbial grain of salt, but some Democrats seem to want to limit impeachment inquiries to the current scandal involving Trump's interactions with the Ukrainian president. I think that is a huge mistake- any impeachment hearings should involve a broad spectrum investigation of multiple scandals, perhaps with a focus of violations of the emoluments clause and his self-dealing, which is looting the treasury. By playing up these scandals, rather than focusing the Ukraine kerfuffle, the Democrats can point out that Republicans are the party of neither strict Constitutionalism nor fiscally responsibility.
This is a brawl, and the Democrats need to treat it as such- they need to hit Trump again and again, to hit him with everything they've got until he's beaten... irrevocably. If they screw up impeachment efforts, they will enrage their own base while emboldening Trump's base. The Republicans didn't waffle when it came to investigating Hillary Clinton for the Benghazi attacks, they kept dragging her in front of Congress again and again. Decades earlier, they kept investigation Bill Clinton until they found something that would stick, if you'll pardon the expression.
The Democrats need to walk and chew gum at the same time, there are mountains of evidence against Trump, evidence of corruption so rampant that it's ubiquitous... and all of it should be investigated. By limiting their investigation to one aspect of this maladministration, they are only hurting themselves... tragically, this seems to be what the Democrats in Congress seem to do best.