If the Dems can take the house they can then:
Reveal the facts on the Kavanaugh/FBI so-called investigation

Investigate the hell out of everything, keeping in mind that the Republicans have spent, at least, 100 million investigating the Clintons.
https://www.quora.com/How-much-money-has...-investigations

Investigate, and report, on markets, jobs, and businesses suffering due to Jackass trade policies.

Investigate the failure of Jackass appointees

ETC. (there is a LOT more!)